diff --git a/source/vibe/core/net.d b/source/vibe/core/net.d
index 29c306a..2473674 100644
--- a/source/vibe/core/net.d
+++ b/source/vibe/core/net.d
@@ -13,6 +13,7 @@ import std.format : format;
 import std.functional : toDelegate;
 import std.socket : AddressFamily, UnknownAddress;
 import vibe.core.log;
+import vibe.core.stream;
 import vibe.internal.async;
 import core.time : Duration;
  
@@ -441,9 +442,10 @@ mixin(tracer);
 mixin(tracer);
 	}
 	void finalize() {}
-	void write(InputStream)(InputStream stream, ulong nbytes = 0) { writeDefault(stream, nbytes); }
+	void write(InputStream)(InputStream stream, ulong nbytes = 0) if (isInputStream!InputStream) { writeDefault(stream, nbytes); }
 
 	private void writeDefault(InputStream)(InputStream stream, ulong nbytes = 0)
+		if (isInputStream!InputStream)
 	{
 		import std.algorithm.comparison : min;
 
diff --git a/source/vibe/core/stream.d b/source/vibe/core/stream.d
new file mode 100644
index 0000000..86fc122
--- /dev/null
+++ b/source/vibe/core/stream.d
@@ -0,0 +1,16 @@
+module vibe.core.stream;
+
+enum isInputStream(T) = __traits(compiles, {
+	T s;
+	ubyte[] buf;
+	if (!s.empty)
+		s.read(buf);
+	if (s.leastSize > 0)
+		s.read(buf);
+});
+
+enum isOutputStream(T) = __traits(compiles, {
+	T s;
+	const(ubyte)[] buf;
+	s.write(buf);
+});