diff --git a/Python/modsupport.c b/Python/modsupport.c
index 845bdcb..13482c6 100644
--- a/Python/modsupport.c
+++ b/Python/modsupport.c
@@ -619,6 +619,9 @@
     va_end(lva);
 
     if (res < 0) {
+        if (stack != small_stack) {
+            PyMem_Free(stack);
+        }
         return NULL;
     }