diff --git a/libsolidity/codegen/CompilerUtils.h b/libsolidity/codegen/CompilerUtils.h
index caf2cdc25..0ee053a99 100644
--- a/libsolidity/codegen/CompilerUtils.h
+++ b/libsolidity/codegen/CompilerUtils.h
@@ -110,10 +110,12 @@ public:
 	void zeroInitialiseMemoryArray(ArrayType const& _type);
 
 	/// Copies full 32 byte words in memory (regions cannot overlap), i.e. may copy more than length.
+	/// Length can be zero, in this case, it copies nothing.
 	/// Stack pre: <size> <target> <source>
 	/// Stack post:
 	void memoryCopy32();
 	/// Copies data in memory (regions cannot overlap).
+	/// Length can be zero, in this case, it copies nothing.
 	/// Stack pre: <size> <target> <source>
 	/// Stack post:
 	void memoryCopy();