--- a/src/util/pmix_pty.c
+++ b/src/util/pmix_pty.c
@@ -97,6 +97,7 @@
 #endif
 
 #include "src/util/pmix_pty.h"
+#include "src/util/pmix_string_copy.h"
 
 /* The only public interface is openpty - all others are to support
    openpty() */