diff --git a/src/fastlock.h b/src/fastlock.h
index e4ab1874f..0809c8bcd 100644
--- a/src/fastlock.h
+++ b/src/fastlock.h
@@ -85,4 +85,6 @@ struct fastlock
 #endif
 };
 
+#ifdef __cplusplus
 static_assert(offsetof(struct fastlock, m_ticket) == 64, "ensure padding is correct");
+#endif
\ No newline at end of file