diff --git a/dyaml/constructor.d b/dyaml/constructor.d
index b745c0a..6ccc3d0 100644
--- a/dyaml/constructor.d
+++ b/dyaml/constructor.d
@@ -22,6 +22,7 @@ import std.exception;
 import std.stdio; 
 import std.regex;
 import std.string;
+import std.typecons;
 import std.utf;
 
 import dyaml.node;
@@ -88,7 +89,8 @@ final class Constructor
          *
          * Params:  defaultConstructors = Use constructors for default YAML tags?
          */
-        this(in bool defaultConstructors = true) @safe nothrow
+        this(const Flag!"useDefaultConstructors" defaultConstructors = Yes.useDefaultConstructors)
+            @safe nothrow
         {
             if(!defaultConstructors){return;}
 
@@ -364,6 +366,7 @@ final class Constructor
                    "Constructor function for tag " ~ tag.get ~ " is already "
                    "specified. Can't specify another one.");
 
+
             return (ref Node n)
             {
                 static if(Node.Value.allowed!T){return Node.Value(ctor(n));}
diff --git a/dyaml/dumper.d b/dyaml/dumper.d
index 3ddf740..9b404b9 100644
--- a/dyaml/dumper.d
+++ b/dyaml/dumper.d
@@ -136,9 +136,9 @@ struct Dumper
         ///Tag directives to use.
         TagDirective[] tags_ = null;
         ///Always write document start?
-        bool explicitStart_ = false;
+        Flag!"explicitStart" explicitStart_ = No.explicitStart;
         ///Always write document end?
-        bool explicitEnd_ = false;
+        Flag!"explicitEnd" explicitEnd_ = No.explicitEnd;
 
         ///Name of the output file or stream, used in error messages.
         string name_ = "<unknown>";
@@ -238,13 +238,13 @@ struct Dumper
         ///Always explicitly write document start?
         @property void explicitStart(bool explicit) pure @safe nothrow
         {
-            explicitStart_ = explicit;
+            explicitStart_ = explicit ? Yes.explicitStart : No.explicitStart;
         }
 
         ///Always explicitly write document end?
         @property void explicitEnd(bool explicit) pure @safe nothrow
         {
-            explicitEnd_ = explicit;
+            explicitEnd_ = explicit ? Yes.explicitEnd : No.explicitEnd;
         }
 
         ///Specify YAML version string. "1.1" by default.
diff --git a/dyaml/emitter.d b/dyaml/emitter.d
index 4b391cf..5751193 100644
--- a/dyaml/emitter.d
+++ b/dyaml/emitter.d
@@ -332,7 +332,7 @@ struct Emitter
 
             encoding_ = event_.encoding;
             writeStreamStart();
-            state_ = &expectDocumentStart!true;
+            state_ = &expectDocumentStart!(Yes.first);
         }
 
         ///Expect nothing, throwing if we still have something.
@@ -344,7 +344,7 @@ struct Emitter
         //Document handlers.
 
         ///Handle start of a document.
-        void expectDocumentStart(bool first)() @trusted
+        void expectDocumentStart(Flag!"first" first)() @trusted
         {
             enforce(eventTypeIs(EventID.DocumentStart) || eventTypeIs(EventID.StreamEnd),
                     new Error("Expected DocumentStart or StreamEnd, but got " 
@@ -423,7 +423,7 @@ struct Emitter
                 writeIndent();
             }
             stream_.flush();
-            state_ = &expectDocumentStart!false;
+            state_ = &expectDocumentStart!(No.first);
         }
 
         ///Handle the root node of a document.
@@ -516,11 +516,11 @@ struct Emitter
             writeIndicator("[", Yes.needWhitespace, Yes.whitespace);
             ++flowLevel_;
             increaseIndent(Yes.flow);
-            state_ = &expectFlowSequenceItem!true;
+            state_ = &expectFlowSequenceItem!(Yes.first);
         }
 
         ///Handle a flow sequence item.
-        void expectFlowSequenceItem(bool first)() @trusted
+        void expectFlowSequenceItem(Flag!"first" first)() @trusted
         {
             if(event_.id == EventID.SequenceEnd)
             {
@@ -537,7 +537,7 @@ struct Emitter
             }
             static if(!first){writeIndicator(",", No.needWhitespace);}
             if(canonical_ || column_ > bestWidth_){writeIndent();}
-            states_ ~= &expectFlowSequenceItem!false;
+            states_ ~= &expectFlowSequenceItem!(No.first);
             expectSequenceNode();
         }
 
@@ -549,11 +549,11 @@ struct Emitter
             writeIndicator("{", Yes.needWhitespace, Yes.whitespace);
             ++flowLevel_;
             increaseIndent(Yes.flow);
-            state_ = &expectFlowMappingKey!true;
+            state_ = &expectFlowMappingKey!(Yes.first);
         }
 
         ///Handle a key in a flow mapping.
-        void expectFlowMappingKey(bool first)() @trusted
+        void expectFlowMappingKey(Flag!"first" first)() @trusted
         {
             if(event_.id == EventID.MappingEnd)
             {
@@ -587,7 +587,7 @@ struct Emitter
         void expectFlowMappingSimpleValue() @trusted
         {
             writeIndicator(":", No.needWhitespace);
-            states_ ~= &expectFlowMappingKey!false;
+            states_ ~= &expectFlowMappingKey!(No.first);
             expectMappingNode();
         }
 
@@ -596,7 +596,7 @@ struct Emitter
         {
             if(canonical_ || column_ > bestWidth_){writeIndent();}
             writeIndicator(":", Yes.needWhitespace);
-            states_ ~= &expectFlowMappingKey!false;
+            states_ ~= &expectFlowMappingKey!(No.first);
             expectMappingNode();
         }
 
@@ -608,11 +608,11 @@ struct Emitter
             const indentless = (context_ == Context.MappingNoSimpleKey ||
                                 context_ == Context.MappingSimpleKey) && !indentation_;
             increaseIndent(No.flow, indentless);
-            state_ = &expectBlockSequenceItem!true;
+            state_ = &expectBlockSequenceItem!(Yes.first);
         }
 
         ///Handle a block sequence item.
-        void expectBlockSequenceItem(bool first)() @trusted
+        void expectBlockSequenceItem(Flag!"first" first)() @trusted
         {
             static if(!first) if(event_.id == EventID.SequenceEnd)
             {
@@ -623,7 +623,7 @@ struct Emitter
 
             writeIndent();
             writeIndicator("-", Yes.needWhitespace, No.whitespace, Yes.indentation);
-            states_ ~= &expectBlockSequenceItem!false;
+            states_ ~= &expectBlockSequenceItem!(No.first);
             expectSequenceNode();
         }
 
@@ -633,11 +633,11 @@ struct Emitter
         void expectBlockMapping() @safe
         {
             increaseIndent(No.flow);
-            state_ = &expectBlockMappingKey!true;
+            state_ = &expectBlockMappingKey!(Yes.first);
         }
 
         ///Handle a key in a block mapping.
-        void expectBlockMappingKey(bool first)() @trusted
+        void expectBlockMappingKey(Flag!"first" first)() @trusted
         {
             static if(!first) if(event_.id == EventID.MappingEnd)
             {
@@ -663,7 +663,7 @@ struct Emitter
         void expectBlockMappingSimpleValue() @trusted
         {
             writeIndicator(":", No.needWhitespace);
-            states_ ~= &expectBlockMappingKey!false;
+            states_ ~= &expectBlockMappingKey!(No.first);
             expectMappingNode();
         }
 
@@ -672,7 +672,7 @@ struct Emitter
         {
             writeIndent();
             writeIndicator(":", Yes.needWhitespace, No.whitespace, Yes.indentation);
-            states_ ~= &expectBlockMappingKey!false;
+            states_ ~= &expectBlockMappingKey!(No.first);
             expectMappingNode();
         }
 
diff --git a/dyaml/event.d b/dyaml/event.d
index 785e804..0a346ca 100644
--- a/dyaml/event.d
+++ b/dyaml/event.d
@@ -95,6 +95,8 @@ struct Event
 
     ///Get string representation of the token ID.
     @property string idString() const @system {return to!string(id);}
+
+    static assert(Event.sizeof <= 48, "Event struct larger than expected");
 }
 
 /**
@@ -178,7 +180,7 @@ alias collectionStartEvent!(EventID.MappingStart)  mappingStartEvent;
  *          YAMLVersion   = YAML version string of the document.
  *          tagDirectives = Tag directives of the document.
  */
-Event documentStartEvent(const Mark start, const Mark end, bool explicit, string YAMLVersion,
+Event documentStartEvent(const Mark start, const Mark end, const bool explicit, string YAMLVersion,
                          TagDirective[] tagDirectives) pure @trusted nothrow
 {
     Event result;
@@ -198,7 +200,7 @@ Event documentStartEvent(const Mark start, const Mark end, bool explicit, string
  *          end      = End position of the event in the file/stream.
  *          explicit = Is this an explicit document end?
  */
-Event documentEndEvent(const Mark start, const Mark end, bool explicit) pure @trusted nothrow
+Event documentEndEvent(const Mark start, const Mark end, const bool explicit) pure @trusted nothrow
 {
     Event result;
     result.startMark        = start;
diff --git a/dyaml/node.d b/dyaml/node.d
index b9207aa..4e09031 100644
--- a/dyaml/node.d
+++ b/dyaml/node.d
@@ -155,7 +155,7 @@ struct Node
                 ///Equality test with another Pair.
                 bool opEquals(const ref Pair rhs) const @safe
                 {
-                    return cmp!true(rhs) == 0;
+                    return cmp!(Yes.useTag)(rhs) == 0;
                 } 
 
             private:
@@ -165,7 +165,7 @@ struct Node
                  * useTag determines whether or not we consider node tags 
                  * in the comparison.
                  */
-                int cmp(bool useTag)(ref const(Pair) rhs) const @safe
+                int cmp(Flag!"useTag" useTag)(ref const(Pair) rhs) const @safe
                 {
                     const keyCmp = key.cmp!useTag(rhs.key);
                     return keyCmp != 0 ? keyCmp
@@ -493,7 +493,7 @@ struct Node
          */
         bool opEquals(T)(const auto ref T rhs) const @safe
         {
-            return equals!true(rhs);
+            return equals!(Yes.useTag)(rhs);
         }
         unittest
         {
@@ -605,7 +605,7 @@ struct Node
                     else if(isFloat()){return to!T(value_.get!(const real));}
                 }
                 else static if(isIntegral!T) if(isInt())
-                {                
+                {
                     const temp = value_.get!(const long);
                     enforce(temp >= T.min && temp <= T.max,
                             new Error("Integer value of type " ~ typeid(T).toString ~ 
@@ -676,7 +676,7 @@ struct Node
                     else if(isFloat()){return to!T(value_.get!(const real));}
                 }
                 else static if(isIntegral!T) if(isInt())
-                {                
+                {
                     const temp = value_.get!(const long);
                     enforce(temp >= T.min && temp <= T.max,
                             new Error("Integer value of type " ~ typeid(T).toString ~ 
@@ -1056,7 +1056,7 @@ struct Node
                     V tempValue = pair.value.as!V;
                     result = dg(tempKey, tempValue);
                 }
-                    
+
                 if(result){break;}
             }
             return result;
@@ -1134,7 +1134,7 @@ struct Node
 
             auto nodes = get!(Node[])();
             static if(is(Unqual!T == Node)){nodes ~= value;}
-            else                    {nodes ~= Node(value);}
+            else                           {nodes ~= Node(value);}
             value_ = Value(nodes);
         }
         unittest
@@ -1278,7 +1278,7 @@ struct Node
         ///Compare with another _node.
         int opCmp(ref const Node node) const @safe
         {
-            return cmp!true(node);
+            return cmp!(Yes.useTag)(node);
         }
 
         //Compute hash of the node.
@@ -1341,7 +1341,7 @@ struct Node
          *
          * useTag determines whether or not to consider tags in node-node comparisons.
          */
-        bool equals(bool useTag, T)(ref T rhs) const @safe
+        bool equals(Flag!"useTag" useTag, T)(ref T rhs) const @safe
         {
             static if(is(Unqual!T == Node))
             {
@@ -1373,7 +1373,7 @@ struct Node
          *
          * useTag determines whether or not to consider tags in the comparison.
          */
-        int cmp(bool useTag)(const ref Node rhs) const @trusted
+        int cmp(Flag!"useTag" useTag)(const ref Node rhs) const @trusted
         {
             //Compare tags - if equal or both null, we need to compare further.
             static if(useTag)
@@ -1591,7 +1591,7 @@ struct Node
 
             if(isMapping)
             {
-                return findPair!(T, !key)(rhs) >= 0;
+                return findPair!(T, key)(rhs) >= 0;
             }
 
             throw new Error("Trying to use " ~ func ~ "() on a " ~ nodeTypeString ~ " node",
@@ -1637,20 +1637,20 @@ struct Node
             }
             else if(isMapping())
             {
-                const index = findPair!(T, !key)(rhs);
+                const index = findPair!(T, key)(rhs);
                 if(index >= 0){removeElem!Pair(this, index);}
             }
         }
 
-        //Get index of pair with key (or value, if value is true) matching index.
-        sizediff_t findPair(T, bool value = false)(const ref T index) const @safe
+        //Get index of pair with key (or value, if key is false) matching index.
+        sizediff_t findPair(T, Flag!"key" key = Yes.key)(const ref T index) const @safe
         {
             const pairs = value_.get!(const Pair[])();
             const(Node)* node;
             foreach(idx, ref const(Pair) pair; pairs)
             {
-                static if(value){node = &pair.value;}
-                else{node = &pair.key;}
+                static if(key){node = &pair.key;}
+                else          {node = &pair.value;}
 
 
                 bool typeMatch = (isFloatingPoint!T && (node.isInt || node.isFloat)) || 
diff --git a/dyaml/parser.d b/dyaml/parser.d
index c0f268f..ece0f21 100644
--- a/dyaml/parser.d
+++ b/dyaml/parser.d
@@ -411,7 +411,8 @@ final class Parser
          */
 
         ///Parse a node.
-        Event parseNode(in bool block, in bool indentlessSequence = false) @safe
+        Event parseNode(const Flag!"block" block,
+                        const Flag!"indentlessSequence" indentlessSequence = No.indentlessSequence) @safe
         {
             if(scanner_.checkToken(TokenID.Alias))
             {
@@ -426,12 +427,12 @@ final class Parser
             bool invalidMarks = true;
 
             //Get anchor/tag if detected. Return false otherwise.
-            bool get(TokenID id, bool start, ref string target)
+            bool get(const TokenID id, const Flag!"first" first, ref string target)
             {
                 if(!scanner_.checkToken(id)){return false;}
                 invalidMarks = false;
                 immutable token = scanner_.getToken();
-                if(start){startMark = token.startMark;}
+                if(first){startMark = token.startMark;}
                 if(id == TokenID.Tag){tagMark = token.startMark;}
                 endMark = token.endMark; 
                 target  = token.value;
@@ -439,8 +440,8 @@ final class Parser
             }
 
             //Anchor and/or tag can be in any order.
-            if(get(TokenID.Anchor, true, anchor)){get(TokenID.Tag, false, tag);}
-            else if(get(TokenID.Tag, true, tag)) {get(TokenID.Anchor, false, anchor);}
+            if(get(TokenID.Anchor, Yes.first, anchor)){get(TokenID.Tag, No.first, tag);}
+            else if(get(TokenID.Tag, Yes.first, tag)) {get(TokenID.Anchor, No.first, anchor);}
 
             if(tag !is null){tag = processTag(tag, startMark, tagMark);}
 
@@ -454,9 +455,9 @@ final class Parser
             if(indentlessSequence && scanner_.checkToken(TokenID.BlockEntry))
             {
                 state_ = &parseIndentlessSequenceEntry;
-                return sequenceStartEvent(startMark, scanner_.peekToken().endMark,
-                                          Anchor(anchor), Tag(tag), implicit,
-                                          CollectionStyle.Block);
+                return sequenceStartEvent
+                    (startMark, scanner_.peekToken().endMark, Anchor(anchor),
+                     Tag(tag), implicit, CollectionStyle.Block);
             }
 
             if(scanner_.checkToken(TokenID.Scalar))
@@ -473,7 +474,7 @@ final class Parser
             if(scanner_.checkToken(TokenID.FlowSequenceStart))
             {
                 endMark = scanner_.peekToken().endMark;
-                state_ = &parseFlowSequenceEntry!true;
+                state_ = &parseFlowSequenceEntry!(Yes.first);
                 return sequenceStartEvent(startMark, endMark, Anchor(anchor), Tag(tag), 
                                           implicit, CollectionStyle.Flow);
             }
@@ -481,7 +482,7 @@ final class Parser
             if(scanner_.checkToken(TokenID.FlowMappingStart))
             {
                 endMark = scanner_.peekToken().endMark;
-                state_ = &parseFlowMappingKey!true;
+                state_ = &parseFlowMappingKey!(Yes.first);
                 return mappingStartEvent(startMark, endMark, Anchor(anchor), Tag(tag), 
                                          implicit, CollectionStyle.Flow);
             }
@@ -489,7 +490,7 @@ final class Parser
             if(block && scanner_.checkToken(TokenID.BlockSequenceStart))
             {
                 endMark = scanner_.peekToken().endMark;
-                state_ = &parseBlockSequenceEntry!true;
+                state_ = &parseBlockSequenceEntry!(Yes.first);
                 return sequenceStartEvent(startMark, endMark, Anchor(anchor), Tag(tag), 
                                           implicit, CollectionStyle.Block);
             }
@@ -497,7 +498,7 @@ final class Parser
             if(block && scanner_.checkToken(TokenID.BlockMappingStart))
             {
                 endMark = scanner_.peekToken().endMark;
-                state_ = &parseBlockMappingKey!true;
+                state_ = &parseBlockMappingKey!(Yes.first);
                 return mappingStartEvent(startMark, endMark, Anchor(anchor), Tag(tag), 
                                          implicit, CollectionStyle.Block);
             }
@@ -557,14 +558,14 @@ final class Parser
         }
 
         ///Wrappers to parse nodes.
-        Event parseBlockNode() @safe {return parseNode(true);}
-        Event parseFlowNode() @safe {return parseNode(false);}
-        Event parseBlockNodeOrIndentlessSequence() @safe {return parseNode(true, true);}
+        Event parseBlockNode() @safe {return parseNode(Yes.block);}
+        Event parseFlowNode() @safe {return parseNode(No.block);}
+        Event parseBlockNodeOrIndentlessSequence() @safe {return parseNode(Yes.block, Yes.indentlessSequence);}
 
         ///block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
 
         ///Parse an entry of a block sequence. If first is true, this is the first entry.
-        Event parseBlockSequenceEntry(bool first)() @trusted
+        Event parseBlockSequenceEntry(Flag!"first" first)() @trusted
         {
             static if(first){marks_ ~= scanner_.getToken().startMark;}
 
@@ -573,11 +574,11 @@ final class Parser
                 immutable token = scanner_.getToken();
                 if(!scanner_.checkToken(TokenID.BlockEntry, TokenID.BlockEnd))
                 {
-                    states_~= &parseBlockSequenceEntry!false;
+                    states_~= &parseBlockSequenceEntry!(No.first);
                     return parseBlockNode();
                 }
 
-                state_ = &parseBlockSequenceEntry!false;
+                state_ = &parseBlockSequenceEntry!(No.first);
                 return processEmptyScalar(token.endMark);
             }
 
@@ -628,7 +629,7 @@ final class Parser
          */
 
         ///Parse a key in a block mapping. If first is true, this is the first key.
-        Event parseBlockMappingKey(bool first)() @trusted
+        Event parseBlockMappingKey(Flag!"first" first)() @trusted
         {
             static if(first){marks_ ~= scanner_.getToken().startMark;}
 
@@ -669,15 +670,15 @@ final class Parser
 
                 if(!scanner_.checkToken(TokenID.Key, TokenID.Value, TokenID.BlockEnd))
                 {
-                    states_ ~= &parseBlockMappingKey!false;
+                    states_ ~= &parseBlockMappingKey!(No.first);
                     return parseBlockNodeOrIndentlessSequence();
                 }
 
-                state_ = &parseBlockMappingKey!false;
+                state_ = &parseBlockMappingKey!(No.first);
                 return processEmptyScalar(token.endMark);
             }
 
-            state_= &parseBlockMappingKey!false;
+            state_= &parseBlockMappingKey!(No.first);
             return processEmptyScalar(scanner_.peekToken().startMark);
         }
 
@@ -695,7 +696,7 @@ final class Parser
          */
 
         ///Parse an entry in a flow sequence. If first is true, this is the first entry.
-        Event parseFlowSequenceEntry(bool first)() @trusted
+        Event parseFlowSequenceEntry(Flag!"first" first)() @trusted
         {
             static if(first){marks_ ~= scanner_.getToken().startMark;}
 
@@ -725,7 +726,7 @@ final class Parser
                 }
                 else if(!scanner_.checkToken(TokenID.FlowSequenceEnd))
                 {
-                    states_ ~= &parseFlowSequenceEntry!false;
+                    states_ ~= &parseFlowSequenceEntry!(No.first);
                     return parseFlowNode();
                 }
             }
@@ -789,7 +790,7 @@ final class Parser
         ///Parse end of a mapping in a flow sequence entry.
         Event parseFlowSequenceEntryMappingEnd() @safe
         {
-            state_ = &parseFlowSequenceEntry!false;
+            state_ = &parseFlowSequenceEntry!(No.first);
             immutable token = scanner_.peekToken();
             return mappingEndEvent(token.startMark, token.startMark);
         }
@@ -803,7 +804,7 @@ final class Parser
          */
 
         ///Parse a key in a flow mapping.
-        Event parseFlowMappingKey(bool first)() @trusted
+        Event parseFlowMappingKey(Flag!"first" first)() @trusted
         {
             static if(first){marks_ ~= scanner_.getToken().startMark;}
 
@@ -845,13 +846,13 @@ final class Parser
         ///Parse a value in a flow mapping.
         Event parseFlowMappingValue()  @safe
         {
-            return parseFlowValue(TokenID.FlowMappingEnd, &parseFlowMappingKey!false);
+            return parseFlowValue(TokenID.FlowMappingEnd, &parseFlowMappingKey!(No.first));
         }
 
         ///Parse an empty value in a flow mapping.
         Event parseFlowMappingEmptyValue() @safe
         {
-            state_ = &parseFlowMappingKey!false;
+            state_ = &parseFlowMappingKey!(No.first);
             return processEmptyScalar(scanner_.peekToken().startMark);
         }
 
diff --git a/dyaml/representer.d b/dyaml/representer.d
index 395a724..99a3630 100644
--- a/dyaml/representer.d
+++ b/dyaml/representer.d
@@ -23,6 +23,7 @@ import std.exception;
 import std.format;
 import std.math;
 import std.stream;
+import std.typecons;
 
 import dyaml.exception;
 import dyaml.node;
@@ -66,7 +67,8 @@ final class Representer
          *                                   disabled to use custom representer
          *                                   functions for default types.
          */
-        this(bool useDefaultRepresenters = true) @safe
+        this(const Flag!"useDefaultRepresenters" useDefaultRepresenters = Yes.useDefaultRepresenters) 
+            @safe
         {
             if(!useDefaultRepresenters){return;}
             addRepresenter!YAMLNull(&representNull);
diff --git a/dyaml/resolver.d b/dyaml/resolver.d
index 32f51e1..b741cdd 100644
--- a/dyaml/resolver.d
+++ b/dyaml/resolver.d
@@ -61,7 +61,8 @@ final class Resolver
          *
          * Params:  defaultImplicitResolvers = Use default YAML implicit resolvers?
          */
-        this(bool defaultImplicitResolvers = true) @safe
+        this(Flag!"useDefaultImplicitResolvers" defaultImplicitResolvers = Yes.useDefaultImplicitResolvers) 
+            @safe
         {
             defaultScalarTag_   = Tag("tag:yaml.org,2002:str");
             defaultSequenceTag_ = Tag("tag:yaml.org,2002:seq");
@@ -142,7 +143,8 @@ final class Resolver
          *
          * Returns: Resolved tag.
          */
-        Tag resolve(NodeID kind, Tag tag, string value, bool implicit) @safe 
+        Tag resolve(const NodeID kind, const Tag tag, const string value, 
+                    const bool implicit) @safe 
         {
             if(!tag.isNull() && tag.get() != "!"){return tag;}
 
diff --git a/dyaml/serializer.d b/dyaml/serializer.d
index e37d01a..30921d6 100644
--- a/dyaml/serializer.d
+++ b/dyaml/serializer.d
@@ -39,9 +39,9 @@ struct Serializer
         Resolver resolver_;
 
         ///Do all document starts have to be specified explicitly?
-        bool explicitStart_;
+        Flag!"explicitStart" explicitStart_;
         ///Do all document ends have to be specified explicitly?
-        bool explicitEnd_;
+        Flag!"explicitEnd" explicitEnd_;
         ///YAML version string.
         string YAMLVersion_;
 
@@ -69,14 +69,15 @@ struct Serializer
          *          tagDirectives = Tag directives to emit. 
          */
         this(ref Emitter emitter, Resolver resolver, Encoding encoding,
-             in bool explicitStart, in bool explicitEnd, string YAMLVersion, 
+             const Flag!"explicitStart" explicitStart, 
+             const Flag!"explicitEnd" explicitEnd, string YAMLVersion, 
              TagDirective[] tagDirectives) @trusted
         {
-            emitter_ = &emitter;
-            resolver_ = resolver;
+            emitter_       = &emitter;
+            resolver_      = resolver;
             explicitStart_ = explicitStart;
-            explicitEnd_ = explicitEnd;
-            YAMLVersion_ = YAMLVersion;
+            explicitEnd_   = explicitEnd;
+            YAMLVersion_   = YAMLVersion;
             tagDirectives_ = tagDirectives;
 
             emitter_.emit(streamStartEvent(Mark(), Mark(), encoding));
diff --git a/test/src/constructor.d b/test/src/constructor.d
index 0b67e87..fca147c 100644
--- a/test/src/constructor.d
+++ b/test/src/constructor.d
@@ -11,6 +11,7 @@ import std.datetime;
 import std.exception;
 import std.path;
 import std.string;
+import std.typecons;
 
 import dyaml.tag;
 import dyaml.testcommon;
@@ -402,7 +403,7 @@ void testConstructor(bool verbose, string dataFilename, string codeDummy)
     size_t i = 0;
     foreach(node; loader)
     {
-        if(!node.equals!false(exp[i]))
+        if(!node.equals!(No.useTag)(exp[i]))
         {
             if(verbose)
             {
diff --git a/test/src/representer.d b/test/src/representer.d
index d7cccee..4281b0c 100644
--- a/test/src/representer.d
+++ b/test/src/representer.d
@@ -9,6 +9,7 @@ module dyaml.testrepresenter;
 
 import std.path;
 import std.exception;
+import std.typecons;
 
 import dyaml.testcommon;
 import dyaml.testconstructor;
@@ -69,7 +70,7 @@ void testRepresenterTypes(bool verbose, string codeFilename)
         assert(expectedNodes.length == readNodes.length);
         foreach(n; 0 .. expectedNodes.length)
         {
-            assert(expectedNodes[n].equals!false(readNodes[n]));
+            assert(expectedNodes[n].equals!(No.useTag)(readNodes[n]));
         }
     }
 }