diff --git a/Python/compile.c b/Python/compile.c
index 9f15254aab0..a01e72ad91c 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -2139,8 +2139,9 @@ com_argdefs(c, n)
 		nargs++;
 		i++;
 		if (i >= nch)
-			break;
-		t = TYPE(CHILD(n, i));
+			t = RPAR; /* Anything except EQUAL or COMMA */
+		else
+			t = TYPE(CHILD(n, i));
 		if (t == EQUAL) {
 			i++;
 			ndefs++;