diff --git a/Python/pystate.c b/Python/pystate.c
index 2a9b744..fe5de5f 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -234,7 +234,7 @@
 	if (!def)
 		return -1;
 	if (!state->modules_by_index) {
-		state->modules_by_index = PyList_New(20);
+		state->modules_by_index = PyList_New(0);
 		if (!state->modules_by_index)
 			return -1;
 	}