diff --git a/src/core/abstract.c b/src/core/abstract.c
index 216ee250..407e9ced 100644
--- a/src/core/abstract.c
+++ b/src/core/abstract.c
@@ -32,7 +32,7 @@
 #ifdef JANET_WINDOWS
 #include <windows.h>
 #else
-//#include <stdatomic.h>
+#include <stdatomic.h>
 #endif
 #endif