Index: src/CodeGen/GenType.cc
===================================================================
--- src/CodeGen/GenType.cc	(revision 0589e83d12bef5409ba2bb4eb9afaa0e0986ead4)
+++ src/CodeGen/GenType.cc	(revision 934fa0fc6af3737f7f5b45e08f4b84e1e8259312)
@@ -23,4 +23,5 @@
 #include "CodeGenerator.h"        // for CodeGenerator
 #include "CodeGeneratorNew.hpp"   // for CodeGenerator_new
+#include "Common/UniqueName.h"    // for UniqueName
 #include "SynTree/Declaration.h"  // for DeclarationWithType
 #include "SynTree/Expression.h"   // for Expression
@@ -662,6 +663,7 @@
 	if ( cur == end ) return "";
 	std::ostringstream oss;
-	for ( unsigned int i = 0 ; ; ++i ) {
-		oss << genType( *cur++, "__param_" + std::to_string(i), options );
+	UniqueName param( "__param_" );
+	while ( true ) {
+		oss << genType( *cur++, options.genC ? param.newName() : "", options );
 		if ( cur == end ) break;
 		oss << ", ";