diff --git a/CMakeLists.txt b/CMakeLists.txt
index e37b5083..d0d03991 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -67,6 +67,7 @@ if(MI_OVERRIDE MATCHES "ON")
       # use zone's on macOS
       message(STATUS "  Use malloc zone to override malloc (MI_OSX_ZONE=ON)")
       list(APPEND mi_sources src/alloc-override-osx.c)
+      list(APPEND mi_defines MI_OSX_ZONE=1)
       if(NOT MI_INTERPOSE MATCHES "ON")
         message(STATUS "  (enabling INTERPOSE as well since zone's require this)")
         set(MI_INTERPOSE "ON")
diff --git a/src/static.c b/src/static.c
index ec9370eb..bf86166d 100644
--- a/src/static.c
+++ b/src/static.c
@@ -24,5 +24,8 @@ terms of the MIT license. A copy of the license can be found in the file
 #include "alloc.c"
 #include "alloc-aligned.c"
 #include "alloc-posix.c"
+#if MI_OSX_ZONE
+#include "alloc-override-osx.c"
+#endif
 #include "init.c"
 #include "options.c"