diff --git a/src/cmd/go/alldocs.go b/src/cmd/go/alldocs.go
index dde47ac1b8..7800c72af3 100644
--- a/src/cmd/go/alldocs.go
+++ b/src/cmd/go/alldocs.go
@@ -3116,6 +3116,7 @@
 //
 //	-benchmem
 //	    Print memory allocation statistics for benchmarks.
+//	    Allocations made in C or using C.malloc are not counted.
 //
 //	-blockprofile block.out
 //	    Write a goroutine blocking profile to the specified file
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index f1555fd5d4..ac9d2721f5 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -353,6 +353,7 @@ profile the tests during execution:
 
 	-benchmem
 	    Print memory allocation statistics for benchmarks.
+	    Allocations made in C or using C.malloc are not counted.
 
 	-blockprofile block.out
 	    Write a goroutine blocking profile to the specified file