diff --git a/src/posix.cpp b/src/posix.cpp
index c0773a46df..635c7c088d 100644
--- a/src/posix.cpp
+++ b/src/posix.cpp
@@ -1,5 +1,6 @@
 #ifdef __APPLE__
 #include "CoreFoundation/CoreFoundation.h"
+#undef assert
 #endif
 #include "sys/mman.h"
 #include "sys/types.h"
diff --git a/src/system.h b/src/system.h
index bb53cdc407..2f06357cbf 100644
--- a/src/system.h
+++ b/src/system.h
@@ -134,7 +134,6 @@ expect(System* s, bool v)
 
 #ifdef NDEBUG
 
-# undef assert
 # define assert(a, b)
 
 #else // not NDEBUG