Index: Python/pystate.c
===================================================================
--- Python/pystate.c	(revision 64979)
+++ Python/pystate.c	(working copy)
@@ -233,7 +233,7 @@
 	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;
 	}