diff --git a/libs/gtkmm2ext/gtk_ui.cc b/libs/gtkmm2ext/gtk_ui.cc
index 8fa9085554..59e678d170 100644
--- a/libs/gtkmm2ext/gtk_ui.cc
+++ b/libs/gtkmm2ext/gtk_ui.cc
@@ -26,7 +26,6 @@
 #include <cmath>
 #include <fcntl.h>
 #include <signal.h>
-#include <unistd.h>
 #include <cerrno>
 #include <climits>
 #include <cctype>