diff --git a/src/core/lib/iomgr/lockfree_event.h b/src/core/lib/iomgr/lockfree_event.h
index 32eb7554f96dcae8bfa47e192681afa17c0cc107..1d9119204cab9da541795dd1d44590aa6aab6ea3 100644
--- a/src/core/lib/iomgr/lockfree_event.h
+++ b/src/core/lib/iomgr/lockfree_event.h
@@ -36,6 +36,8 @@
 
 /* Lock free event notification for file descriptors */
 
+#include <grpc/support/atm.h>
+
 #include "src/core/lib/iomgr/exec_ctx.h"
 
 void grpc_lfev_init(gpr_atm *state);