diff --git a/mfbt/Assertions.h b/mfbt/Assertions.h
index 25d7d8ebd207..407fb24e98d1 100644
--- a/mfbt/Assertions.h
+++ b/mfbt/Assertions.h
@@ -9,8 +9,8 @@
 #define mozilla_Assertions_h_
 
 #include "mozilla/Attributes.h"
-#include "mozilla/Types.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #ifdef WIN32
diff --git a/mfbt/HashFunctions.cpp b/mfbt/HashFunctions.cpp
index 199e265de52e..28d4c9f4022b 100644
--- a/mfbt/HashFunctions.cpp
+++ b/mfbt/HashFunctions.cpp
@@ -6,6 +6,7 @@
 /* Implementations of hash functions. */
 
 #include "mozilla/HashFunctions.h"
+#include "mozilla/Types.h"
 
 #include <string.h>
 
diff --git a/mfbt/HashFunctions.h b/mfbt/HashFunctions.h
index 64ac6f91ce5c..7a19749e556d 100644
--- a/mfbt/HashFunctions.h
+++ b/mfbt/HashFunctions.h
@@ -48,6 +48,7 @@
 #include "mozilla/Assertions.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/StandardInteger.h"
+#include "mozilla/Types.h"
 
 #ifdef __cplusplus
 namespace mozilla {