diff --git a/src/calamares/DebugWindow.cpp b/src/calamares/DebugWindow.cpp
index 5ccab2c92..e27fc0a7b 100644
--- a/src/calamares/DebugWindow.cpp
+++ b/src/calamares/DebugWindow.cpp
@@ -34,6 +34,7 @@
 #include <QWidget>
 
 #include <signal.h>
+#include <unistd.h>
 
 /**
  * @brief crash makes Calamares crash immediately.