diff --git a/source/dyaml/constructor.d b/source/dyaml/constructor.d
index f7ea296..bd56530 100644
--- a/source/dyaml/constructor.d
+++ b/source/dyaml/constructor.d
@@ -129,7 +129,7 @@ final class Constructor
         void addConstructorScalar(T)(const string tag, T function(ref Node) @safe ctor)
         {
             const t = tag;
-            auto deleg = addConstructor!T(t, ctor);
+            const deleg = addConstructor!T(t, ctor);
             (*delegates!string)[t] = deleg;
         }
         ///
@@ -141,7 +141,7 @@ final class Constructor
 
                 //Any D:YAML type must have a custom opCmp operator.
                 //This is used for ordering in mappings.
-                const int opCmp(ref const MyStruct s)
+                int opCmp(ref const MyStruct s) const
                 {
                     if(x != s.x){return x - s.x;}
                     if(y != s.y){return y - s.y;}
@@ -175,7 +175,7 @@ final class Constructor
         void addConstructorSequence(T)(const string tag, T function(ref Node) @safe ctor)
         {
             const t = tag;
-            auto deleg = addConstructor!T(t, ctor);
+            const deleg = addConstructor!T(t, ctor);
             (*delegates!(Node[]))[t] = deleg;
         }
         ///
@@ -187,7 +187,7 @@ final class Constructor
 
                 //Any D:YAML type must have a custom opCmp operator.
                 //This is used for ordering in mappings.
-                const int opCmp(ref const MyStruct s)
+                int opCmp(ref const MyStruct s) const
                 {
                     if(x != s.x){return x - s.x;}
                     if(y != s.y){return y - s.y;}
@@ -219,7 +219,7 @@ final class Constructor
         void addConstructorMapping(T)(const string tag, T function(ref Node) @safe ctor)
         {
             const t = tag;
-            auto deleg = addConstructor!T(t, ctor);
+            const deleg = addConstructor!T(t, ctor);
             (*delegates!(Node.Pair[]))[t] = deleg;
         }
         ///
@@ -230,7 +230,7 @@ final class Constructor
 
                 //Any D:YAML type must have a custom opCmp operator.
                 //This is used for ordering in mappings.
-                const int opCmp(ref const MyStruct s)
+                int opCmp(ref const MyStruct s) const
                 {
                     if(x != s.x){return x - s.x;}
                     if(y != s.y){return y - s.y;}
@@ -484,7 +484,7 @@ long constructLong(ref Node node) @safe
         //Sexagesimal.
         else if(value.canFind(":"))
         {
-            long val = 0;
+            long val;
             long base = 1;
             foreach_reverse(digit; value.split(":"))
             {
@@ -622,7 +622,7 @@ ubyte[] constructBinary(ref Node node) @safe
     buffer.length = 256;
     string input = Base64.encode(test, buffer).idup;
     auto node = Node(input);
-    auto value = constructBinary(node);
+    const value = constructBinary(node);
     assert(value == test);
     assert(value == [84, 104, 101, 32, 65, 110, 115, 119, 101, 114, 58, 32, 52, 50]);
 }
@@ -661,7 +661,7 @@ SysTime constructTimestamp(ref Node node) @safe
         const hour            = to!int(captures[1]);
         const minute          = to!int(captures[2]);
         const second          = to!int(captures[3]);
-        const hectonanosecond = cast(int)(to!real("0" ~ captures[4]) * 10000000);
+        const hectonanosecond = cast(int)(to!real("0" ~ captures[4]) * 10_000_000);
 
         // If available, get timezone.
         value = matches.front.post;
@@ -676,7 +676,7 @@ SysTime constructTimestamp(ref Node node) @safe
         // We have a timezone, so parse it.
         captures = matches.front.captures;
         int sign    = 1;
-        int tzHours = 0;
+        int tzHours;
         if(!captures[1].empty)
         {
             if(captures[1][0] == '-') {sign = -1;}
diff --git a/source/dyaml/dumper.d b/source/dyaml/dumper.d
index f518c0e..16e4277 100644
--- a/source/dyaml/dumper.d
+++ b/source/dyaml/dumper.d
@@ -47,7 +47,7 @@ struct Dumper
         //Stream to write to.
         YStream stream_;
         //True if this Dumper owns stream_ and needs to destroy it in the destructor.
-        bool weOwnStream_ = false;
+        bool weOwnStream_;
 
         //Write scalars in canonical form?
         bool canonical_;
@@ -62,7 +62,7 @@ struct Dumper
         //YAML version string.
         string YAMLVersion_ = "1.1";
         //Tag directives to use.
-        TagDirective[] tags_ = null;
+        TagDirective[] tags_;
         //Always write document start?
         Flag!"explicitStart" explicitStart_ = No.explicitStart;
         //Always write document end?
diff --git a/source/dyaml/emitter.d b/source/dyaml/emitter.d
index e8e0df6..6572133 100644
--- a/source/dyaml/emitter.d
+++ b/source/dyaml/emitter.d
@@ -260,7 +260,7 @@ struct Emitter
         ///Determines if we need specified number of more events.
         bool needEvents(in uint count) @safe nothrow
         {
-            int level = 0;
+            int level;
 
             //Rather ugly, but good enough for now.
             //Couldn't be bothered writing a range as events_ should eventually
@@ -698,7 +698,7 @@ struct Emitter
         ///Check if a simple key is next.
         bool checkSimpleKey() @safe
         {
-            uint length = 0;
+            uint length;
             const id = event_.id;
             const scalar = id == EventID.Scalar;
             const collectionStart = id == EventID.MappingStart ||
@@ -904,9 +904,8 @@ struct Emitter
                     new EmitterException("Tag prefix must not be empty"));
 
             auto appender = appender!string();
-            const offset = prefix[0] == '!' ? 1 : 0;
-            size_t start = 0;
-            size_t end = 0;
+            const int offset = prefix[0] == '!';
+            size_t start, end;
 
             foreach(const size_t i, const dchar c; prefix)
             {
@@ -935,7 +934,7 @@ struct Emitter
 
             string tagString = tag;
             if(tagString == "!"){return tagString;}
-            string handle = null;
+            string handle;
             string suffix = tagString;
 
             //Sort lexicographically by prefix.
@@ -953,8 +952,7 @@ struct Emitter
 
             auto appender = appender!string();
             appender.put(handle !is null && handle != "" ? handle : "!<");
-            size_t start = 0;
-            size_t end = 0;
+            size_t start, end;
             foreach(const dchar c; suffix)
             {
                 if(isAlphaNum(c) || "-;/?:@&=+$,_.~*\'()[]"d.canFind(c) ||
@@ -1581,8 +1579,9 @@ struct ScalarWriter
         ///Determine hints (indicators) for block scalar.
         size_t determineBlockHints(char[] hints, uint bestIndent) const pure @safe
         {
-            size_t hintsIdx = 0;
-            if(text_.length == 0){return hintsIdx;}
+            size_t hintsIdx;
+            if(text_.length == 0)
+                return hintsIdx;
 
             dchar lastChar(const string str, ref size_t end)
             {
diff --git a/source/dyaml/loader.d b/source/dyaml/loader.d
index 1773d8b..99a8458 100644
--- a/source/dyaml/loader.d
+++ b/source/dyaml/loader.d
@@ -46,7 +46,7 @@ struct Loader
         // Name of the input file or stream, used in error messages.
         string name_ = "<unknown>";
         // Are we done loading?
-        bool done_ = false;
+        bool done_;
 
     public:
         @disable this();
@@ -255,7 +255,7 @@ struct Loader
                 lazyInitConstructorResolver();
                 auto composer = new Composer(parser_, resolver_, constructor_);
 
-                int result = 0;
+                int result;
                 while(composer.checkNode())
                 {
                     auto node = composer.getNode();
diff --git a/source/dyaml/node.d b/source/dyaml/node.d
index 191afb5..010c303 100644
--- a/source/dyaml/node.d
+++ b/source/dyaml/node.d
@@ -67,7 +67,7 @@ package abstract class YAMLObject
 
     protected:
         // Compare with another YAMLObject.
-        int cmp(const YAMLObject rhs) const @system {assert(false);};
+        int cmp(const YAMLObject) const @system {assert(false);}
 }
 
 // Stores a user defined YAML data type.
@@ -967,7 +967,7 @@ struct Node
                 }
 
                 /* Input range functionality. */
-                bool empty() @property { return position >= subnodes.length; }
+                bool empty() const @property { return position >= subnodes.length; }
 
                 void popFront()
                 {
@@ -975,7 +975,7 @@ struct Node
                     position++;
                 }
 
-                T front() @property
+                T front() const @property
                 {
                     enforce(!empty, "Attempted to take the front of an empty sequence");
                     static if (is(Unqual!T == Node))
@@ -1226,7 +1226,7 @@ struct Node
                         new NodeException("Trying to sequence-foreach over a " ~ nodeTypeString ~ " node",
                                   startMark_));
 
-                int result = 0;
+                int result;
                 foreach(ref node; get!(Node[]))
                 {
                     static if(is(Unqual!T == Node))
@@ -1249,7 +1249,7 @@ struct Node
                         new NodeException("Trying to sequence-foreach over a " ~ nodeTypeString ~ " node",
                                   startMark_));
 
-                int result = 0;
+                int result;
                 foreach(ref node; get!(Node[]))
                 {
                     static if(is(Unqual!T == Node))
@@ -1344,7 +1344,7 @@ struct Node
                         new NodeException("Trying to mapping-foreach over a " ~ nodeTypeString ~ " node",
                                   startMark_));
 
-                int result = 0;
+                int result;
                 foreach(ref pair; get!(Node.Pair[]))
                 {
                     static if(is(Unqual!K == Node) && is(Unqual!V == Node))
@@ -1379,7 +1379,7 @@ struct Node
                         new NodeException("Trying to mapping-foreach over a " ~ nodeTypeString ~ " node",
                                   startMark_));
 
-                int result = 0;
+                int result;
                 foreach(ref pair; get!(Node.Pair[]))
                 {
                     static if(is(Unqual!K == Node) && is(Unqual!V == Node))
@@ -2170,7 +2170,7 @@ struct Node
                 else          {node = &pair.value;}
 
 
-                bool typeMatch = (isFloatingPoint!T && (node.isInt || node.isFloat)) ||
+                const bool typeMatch = (isFloatingPoint!T && (node.isInt || node.isFloat)) ||
                                  (isIntegral!T && node.isInt) ||
                                  (is(Unqual!T==bool) && node.isBool) ||
                                  (isSomeString!T && node.isString) ||
diff --git a/source/dyaml/parser.d b/source/dyaml/parser.d
index d7c03d5..63a143d 100644
--- a/source/dyaml/parser.d
+++ b/source/dyaml/parser.d
@@ -379,7 +379,7 @@ final class Parser
             //Add any default tag handles that haven't been overridden.
             foreach(ref defaultPair; defaultTagDirectives_)
             {
-                bool found = false;
+                bool found;
                 foreach(ref pair; tagDirectives_) if(defaultPair.handle == pair.handle)
                 {
                     found = true;
@@ -422,8 +422,8 @@ final class Parser
                                   cast(string)token.value);
             }
 
-            string anchor = null;
-            string tag = null;
+            string anchor;
+            string tag;
             Mark startMark, endMark, tagMark;
             bool invalidMarks = true;
             // The index in the tag string where tag handle ends and tag suffix starts.
@@ -536,7 +536,7 @@ final class Parser
         string handleDoubleQuotedScalarEscapes(char[] tokenValue) const @safe
         {
             string notInPlace;
-            bool inEscape = false;
+            bool inEscape;
             auto appender = appender!(string)();
             for(char[] oldValue = tokenValue; !oldValue.empty();)
             {
@@ -624,7 +624,7 @@ final class Parser
 
             if(handle.length > 0)
             {
-                string replacement = null;
+                string replacement;
                 foreach(ref pair; tagDirectives_)
                 {
                     if(pair.handle == handle)
diff --git a/source/dyaml/reader.d b/source/dyaml/reader.d
index ab54d4d..1fb09d7 100644
--- a/source/dyaml/reader.d
+++ b/source/dyaml/reader.d
@@ -47,15 +47,15 @@ final class Reader
 {
     private:
         // Buffer of currently loaded characters.
-        char[] buffer_ = null;
+        char[] buffer_;
 
         // Current position within buffer. Only data after this position can be read.
-        size_t bufferOffset_ = 0;
+        size_t bufferOffset_;
 
         // Index of the current character in the buffer.
-        size_t charIndex_ = 0;
+        size_t charIndex_;
         // Number of characters (code points) in buffer_.
-        size_t characterCount_ = 0;
+        size_t characterCount_;
 
         // Current line in file.
         uint line_;
@@ -74,13 +74,13 @@ final class Reader
         // The number of consecutive ASCII characters starting at bufferOffset_.
         //
         // Used to minimize UTF-8 decoding.
-        size_t upcomingASCII_ = 0;
+        size_t upcomingASCII_;
 
         // Index to buffer_ where the last decoded character starts.
-        size_t lastDecodedBufferOffset_ = 0;
+        size_t lastDecodedBufferOffset_;
         // Offset, relative to charIndex_, of the last decoded character,
         // in code points, not chars.
-        size_t lastDecodedCharOffset_ = 0;
+        size_t lastDecodedCharOffset_;
 
     public:
         /// Construct a Reader.
@@ -464,7 +464,7 @@ private:
     // Very few levels as we don't want arbitrarily nested transactions.
     size_t[4] endStack_;
     // The number of elements currently in endStack_.
-    size_t endStackUsed_ = 0;
+    size_t endStackUsed_;
 
     @safe const pure nothrow @nogc invariant()
     {
@@ -616,7 +616,7 @@ public:
     {
     private:
         // The slice builder affected by the transaction.
-        SliceBuilder* builder_ = null;
+        SliceBuilder* builder_;
         // Index of the return point of the transaction in StringBuilder.endStack_.
         size_t stackLevel_;
         // True after commit() has been called.
@@ -842,7 +842,7 @@ bool isPrintableValidUTF8(const char[] chars) @safe pure
                            false, false, false, false, false, false, false, false,
                            false, false, false, false, false, false, false, false];
 
-    for(size_t index = 0; index < chars.length;)
+    for(size_t index; index < chars.length;)
     {
         // Fast path for ASCII.
         // Both this while() block and the if() block below it are optimized, unrolled
diff --git a/source/dyaml/scanner.d b/source/dyaml/scanner.d
index b38873d..b569fc4 100644
--- a/source/dyaml/scanner.d
+++ b/source/dyaml/scanner.d
@@ -1792,7 +1792,7 @@ final class Scanner
                 spacesTransaction = Transaction(&reader_.sliceBuilder);
 
                 const startLength = reader_.sliceBuilder.length;
-                scanPlainSpacesToSlice(startMark);
+                scanPlainSpacesToSlice();
                 if(startLength == reader_.sliceBuilder.length ||
                    (flowLevel_ == 0 && reader_.column < indent))
                 {
@@ -1810,7 +1810,7 @@ final class Scanner
         ///
         /// Assumes that the caller is building a slice in Reader, and puts the spaces
         /// into that slice.
-        void scanPlainSpacesToSlice(const Mark startMark) @safe
+        void scanPlainSpacesToSlice() @safe
         {
             // The specification is really confusing about tabs in plain scalars.
             // We just forbid them completely. Do not use tabs in YAML!
diff --git a/source/dyaml/serializer.d b/source/dyaml/serializer.d
index bb10390..7a84d4f 100644
--- a/source/dyaml/serializer.d
+++ b/source/dyaml/serializer.d
@@ -165,7 +165,7 @@ struct Serializer
             //If the node has an anchor, emit an anchor (as aliasEvent) on the
             //first occurrence, save it in serializedNodes_, and emit an alias
             //if it reappears.
-            string aliased = null;
+            string aliased;
             if(anchorable(node) && (node in anchors_) !is null)
             {
                 aliased = anchors_[node];
@@ -182,7 +182,7 @@ struct Serializer
                 assert(node.isType!string, "Scalar node type must be string before serialized");
                 auto value = node.as!string;
                 const detectedTag = resolver_.resolve(NodeID.Scalar, null, value, true);
-                bool isDetected = node.tag_ == detectedTag;
+                const bool isDetected = node.tag_ == detectedTag;
 
                 emitter_.emit(scalarEvent(Mark(), Mark(), aliased, node.tag_,
                               isDetected, value, node.scalarStyle));
diff --git a/source/dyaml/test/common.d b/source/dyaml/test/common.d
index ecad2e5..f0eb00c 100644
--- a/source/dyaml/test/common.d
+++ b/source/dyaml/test/common.d
@@ -198,8 +198,7 @@ void display(Result[] results) @safe
 {
     if(results.length > 0 && !verbose && !quiet){write("\n");}
 
-    size_t failures = 0;
-    size_t errors = 0;
+    size_t failures, errors;
 
     static if(verbose)
     {
diff --git a/source/dyaml/test/constructor.d b/source/dyaml/test/constructor.d
index 2917f09..264795c 100644
--- a/source/dyaml/test/constructor.d
+++ b/source/dyaml/test/constructor.d
@@ -353,7 +353,7 @@ struct TestStruct
 
     //Any D:YAML type must have a custom opCmp operator.
     //This is used for ordering in mappings.
-    const int opCmp(ref const TestStruct s) @safe
+    int opCmp(ref const TestStruct s) const @safe
     {
         return value - s.value;
     }
@@ -414,7 +414,7 @@ void testConstructor(string dataFilename, string codeDummy) @safe
     Node[] exp = expected[base];
 
     //Compare with expected results document by document.
-    size_t i = 0;
+    size_t i;
     foreach(node; loader)
     {
         if(!node.equals!(No.useTag)(exp[i]))
diff --git a/source/dyaml/test/emitter.d b/source/dyaml/test/emitter.d
index 7efde7b..c6fde44 100644
--- a/source/dyaml/test/emitter.d
+++ b/source/dyaml/test/emitter.d
@@ -32,7 +32,7 @@ bool compareEvents(Event[] events1, Event[] events2) @safe
 {
     if(events1.length != events2.length){return false;}
 
-    for(uint e = 0; e < events1.length; ++e)
+    for(uint e; e < events1.length; ++e)
     {
         auto e1 = events1[e];
         auto e2 = events2[e];