diff --git a/interpret.h b/interpret.h
index 9ffa5bbd..4c723ae0 100644
--- a/interpret.h
+++ b/interpret.h
@@ -483,9 +483,10 @@ uninitialized_scalar:
 		case Op_lint_plus:
 			// no need to check do_lint, this opcode won't
 			// be generated if that's not true
-			t1 = TOP();
-			t2 = PEEK(1);
-			if ((t1->flags & STRING) != 0 && (t2->flags & STRING) != 0)
+			t1 = fixtype(TOP());
+			t2 = fixtype(PEEK(1));
+			if ((t1->flags & (STRING|USER_INPUT)) == STRING
+			    && (t2->flags & (STRING|USER_INPUT)) == STRING)
 				lintwarn(_("operator `+' used on two string values"));
 			break;