diff --git a/tools/blisp/src/util.c b/tools/blisp/src/util.c
index 906985a..7263dcf 100644
--- a/tools/blisp/src/util.c
+++ b/tools/blisp/src/util.c
@@ -10,6 +10,7 @@
 // to free an allocated buffer on the caller.nn
 
 #include <stdlib.h>
+#include <mach-o/dyld.h>
 
 static void util_get_executable_path(char* buffer_out, uint32_t max_size) {
   assert(max_size >= PATH_MAX);  // n.b. 1024 on MacOS. 4K on most Linux.