diff --git a/cmd/bench/gotest.go b/cmd/bench/gotest.go
index accf6a0..a98ce20 100644
--- a/cmd/bench/gotest.go
+++ b/cmd/bench/gotest.go
@@ -26,7 +26,7 @@
 		}
 	}
 	if needGOROOT {
-		env = append(env, "GOROOT=" + goroot)
+		env = append(env, "GOROOT="+goroot)
 	}
 	cmd.Env = env