diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index 14381b6e0..31cb3d303 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -9,6 +9,9 @@
 #include <unistd.h>
 #include <errno.h>
 
+#if __APPLE__
+#include <regex>
+#endif
 
 namespace nix {