diff --git a/modules/audio_processing/aec3/clockdrift_detector.h b/modules/audio_processing/aec3/clockdrift_detector.h
index 22528c9489..2ba90bb889 100644
--- a/modules/audio_processing/aec3/clockdrift_detector.h
+++ b/modules/audio_processing/aec3/clockdrift_detector.h
@@ -11,6 +11,8 @@
 #ifndef MODULES_AUDIO_PROCESSING_AEC3_CLOCKDRIFT_DETECTOR_H_
 #define MODULES_AUDIO_PROCESSING_AEC3_CLOCKDRIFT_DETECTOR_H_
 
+#include <stddef.h>
+
 #include <array>
 
 namespace webrtc {