diff --git a/src/backends/drm/drm_qpainter_layer.cpp b/src/backends/drm/drm_qpainter_layer.cpp
index 6131924c1c..003fa5d4b2 100644
--- a/src/backends/drm/drm_qpainter_layer.cpp
+++ b/src/backends/drm/drm_qpainter_layer.cpp
@@ -19,6 +19,7 @@
 #include "drm_qpainter_backend.h"
 #include "drm_virtual_output.h"
 
+#include <cerrno>
 #include <drm_fourcc.h>
 
 namespace KWin
diff --git a/src/backends/x11/windowed/x11_windowed_qpainter_backend.cpp b/src/backends/x11/windowed/x11_windowed_qpainter_backend.cpp
index 62e48df3b4..d86a12e48c 100644
--- a/src/backends/x11/windowed/x11_windowed_qpainter_backend.cpp
+++ b/src/backends/x11/windowed/x11_windowed_qpainter_backend.cpp
@@ -11,6 +11,7 @@
 #include "x11_windowed_logging.h"
 #include "x11_windowed_output.h"
 
+#include <cerrno>
 #include <string.h>
 #include <sys/shm.h>
 #include <xcb/present.h>
diff --git a/src/utils/ramfile.cpp b/src/utils/ramfile.cpp
index e78000b255..79e289283d 100644
--- a/src/utils/ramfile.cpp
+++ b/src/utils/ramfile.cpp
@@ -13,6 +13,7 @@
 
 #include <QScopeGuard>
 
+#include <cerrno>
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <unistd.h>