diff --git a/include/libcamera/geometry.h b/include/libcamera/geometry.h
index d4a144bc..d7fdbe70 100644
--- a/include/libcamera/geometry.h
+++ b/include/libcamera/geometry.h
@@ -8,6 +8,7 @@
 #pragma once
 
 #include <algorithm>
+#include <ostream>
 #include <string>
 
 #include <libcamera/base/compiler.h>