run.go | 9 +++++----

diff --git a/run.go b/run.go
index 674efa6ea3668ff5be867b068afaa7ad5c8a206dc2235adfc9c9503d224a8724..7c2f3263d54ee231ba6bbfaaf4d3a12e163a01f4e17f08db07f2e60f6454d2a8 100644
--- a/run.go
+++ b/run.go
@@ -408,10 +408,11 @@ 			cmd.Env = append(cmd.Env, fmt.Sprintf("%s=NO", EnvJobs))
 		} else {
 			cmd.ExtraFiles = append(cmd.ExtraFiles, JSR)
 			cmd.ExtraFiles = append(cmd.ExtraFiles, JSW)
-			cmd.Env = append(cmd.Env, fmt.Sprintf(
-				"%s=%s %s%d,%d",
-				MakeFlagsName, MakeFlags, MakeJSArg, 3+fdNum+0, 3+fdNum+1,
-			))
+			makeFlags := fmt.Sprintf(
+				"%s %s%d,%d", MakeFlags, MakeJSArg, 3+fdNum+0, 3+fdNum+1,
+			)
+			makeFlags = strings.Trim(makeFlags, " ")
+			cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", MakeFlagsName, makeFlags))
 			fdNum += 2
 			cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%d", EnvJSToken, jsToken))
 		}