diff --git a/src/declaration.c b/src/declaration.c
index 07da5ad94805..679597b38f54 100644
--- a/src/declaration.c
+++ b/src/declaration.c
@@ -1021,7 +1021,7 @@ void VarDeclaration::semantic(Scope *sc)
             Parameter *arg = Parameter::getNth(tt->arguments, i);
 
             OutBuffer buf;
-            buf.printf("_%s_field_%llu", ident->toChars(), (ulonglong)i);
+            buf.printf("__%s_field_%llu", ident->toChars(), (ulonglong)i);
             const char *name = buf.extractString();
             Identifier *id = Lexer::idPool(name);