diff --git a/rtc_base/constructormagic.h b/rtc_base/constructormagic.h
index 646a058ce3..6b6e83cb47 100644
--- a/rtc_base/constructormagic.h
+++ b/rtc_base/constructormagic.h
@@ -12,7 +12,8 @@
 #define RTC_BASE_CONSTRUCTORMAGIC_H_
 
 // Put this in the declarations for a class to be unassignable.
-#define RTC_DISALLOW_ASSIGN(TypeName) void operator=(const TypeName&) = delete
+#define RTC_DISALLOW_ASSIGN(TypeName) \
+  TypeName& operator=(const TypeName&) = delete
 
 // A macro to disallow the copy constructor and operator= functions. This should
 // be used in the declarations for a class.