diff --git a/Compiler/Template/CodegenCpp.tpl b/Compiler/Template/CodegenCpp.tpl
index 151c07061b9..7a44c3e4d95 100644
--- a/Compiler/Template/CodegenCpp.tpl
+++ b/Compiler/Template/CodegenCpp.tpl
@@ -4472,7 +4472,7 @@ template extType2(Type type, Boolean isInput, Boolean isArray)
   let s = match type
   case T_INTEGER(__)         then "int"
   case T_REAL(__)        then "double"
-  case T_STRING(__)      then "string"/*use string instead of char* for external types*/
+  case T_STRING(__)      then "const char*"
   case T_BOOL(__)        then "int"
   case T_ENUMERATION(__) then "int"
   case T_ARRAY(__)       then extType2(ty,isInput,true)