diff --git a/contrib/ldapc++/src/SaslInteractionHandler.cpp b/contrib/ldapc++/src/SaslInteractionHandler.cpp
index 3233ac9fc8..dbccbd5b31 100644
--- a/contrib/ldapc++/src/SaslInteractionHandler.cpp
+++ b/contrib/ldapc++/src/SaslInteractionHandler.cpp
@@ -11,6 +11,7 @@
 
 #ifdef HAVE_TERMIOS_H
 #include <termios.h>
+#include <unistd.h>
 #include <cstdio>
 #endif