diff --git a/libs/ardour/mac_vst_support.cc b/libs/ardour/mac_vst_support.cc
index 2a5efc088c..686c54f747 100644
--- a/libs/ardour/mac_vst_support.cc
+++ b/libs/ardour/mac_vst_support.cc
@@ -24,6 +24,7 @@
 #include <signal.h>
 #include <dlfcn.h>
 #include <string.h>
+#include <strings.h>
 #include <time.h>
 #include <unistd.h>
 #include <pthread.h>