diff --git a/rtc_base/system/unused.h b/rtc_base/system/unused.h
index a0add4ee29..084c526626 100644
--- a/rtc_base/system/unused.h
+++ b/rtc_base/system/unused.h
@@ -11,21 +11,6 @@
 #ifndef RTC_BASE_SYSTEM_UNUSED_H_
 #define RTC_BASE_SYSTEM_UNUSED_H_
 
-// Annotate a function indicating the caller must examine the return value.
-// Use like:
-//   int foo() RTC_WARN_UNUSED_RESULT;
-// To explicitly ignore a result, cast to void.
-// TODO(kwiberg): Remove when we can use [[nodiscard]] from C++17.
-#if defined(__clang__)
-#define RTC_WARN_UNUSED_RESULT __attribute__((__warn_unused_result__))
-#elif defined(__GNUC__)
-// gcc has a __warn_unused_result__ attribute, but you can't quiet it by
-// casting to void, so we don't use it.
-#define RTC_WARN_UNUSED_RESULT
-#else
-#define RTC_WARN_UNUSED_RESULT
-#endif
-
 // Prevent the compiler from warning about an unused variable. For example:
 //   int result = DoSomething();
 //   assert(result == 17);