diff --git a/libs/backends/portaudio/winmmemidi_output_device.h b/libs/backends/portaudio/winmmemidi_output_device.h
index 7f3c8f59b3..a54975109e 100644
--- a/libs/backends/portaudio/winmmemidi_output_device.h
+++ b/libs/backends/portaudio/winmmemidi_output_device.h
@@ -26,6 +26,7 @@
 #include <pthread.h>
 
 #include <string>
+#include <memory>
 
 #include <pbd/ringbuffer.h>