diff --git a/Modules/getpath.c b/Modules/getpath.c
index 2372172..36f9860 100644
--- a/Modules/getpath.c
+++ b/Modules/getpath.c
@@ -1142,7 +1142,7 @@
         return DECODE_LOCALE_ERR("PREFIX define", len);
     }
     calculate->exec_prefix = Py_DecodeLocale(EXEC_PREFIX, &len);
-    if (!calculate->prefix) {
+    if (!calculate->exec_prefix) {
         return DECODE_LOCALE_ERR("EXEC_PREFIX define", len);
     }
     calculate->lib_python = Py_DecodeLocale("lib/python" VERSION, &len);