diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c1d7e8fd167..2abcb43e0ce 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+Sat Apr 17 14:36:19 1999  Craig Burley  <craig@jcb-sc.com>
+
+	* tree.c (chainon): Check for circularity only if
+	ENABLE_CHECKING is defined.
+
 1999-04-17 10:15 -0400  Zack Weinberg  <zack@rabi.columbia.edu>
 
 	* cccp.c: Make fatal non-static.
diff --git a/gcc/tree.c b/gcc/tree.c
index d2594208c84..b61c11587ec 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -1956,9 +1956,11 @@ chainon (op1, op2)
       for (t1 = op1; TREE_CHAIN (t1); t1 = TREE_CHAIN (t1))
 	;
       TREE_CHAIN (t1) = op2;
+#ifdef ENABLE_CHECKING
       for (t2 = op2; t2; t2 = TREE_CHAIN (t2))
         if (t2 == t1)
           abort ();  /* Circularity created.  */
+#endif
       return op1;
     }
   else return op2;