diff --git a/src/runtime/select.go b/src/runtime/select.go
index fccb53b44c..3a3ac6b7ac 100644
--- a/src/runtime/select.go
+++ b/src/runtime/select.go
@@ -191,14 +191,15 @@ func selectgo(cas0 *scase, order0 *uint16, ncases int) (int, bool) {
 		}
 		lockorder[j] = o
 	}
-	/*
+
+	if debugSelect {
 		for i := 0; i+1 < ncases; i++ {
 			if scases[lockorder[i]].c.sortkey() > scases[lockorder[i+1]].c.sortkey() {
 				print("i=", i, " x=", lockorder[i], " y=", lockorder[i+1], "\n")
 				throw("select: broken sort")
 			}
 		}
-	*/
+	}
 
 	// lock all the channels involved in the select
 	sellock(scases, lockorder)