diff --git a/gcc/tree-ssa-loop-niter.cc b/gcc/tree-ssa-loop-niter.cc
index 7743970bf3d59882d34349b6eb80c4d873d5b9d0..9ce88134414203b5160ccf1524d17e5812bc7abc 100644
--- a/gcc/tree-ssa-loop-niter.cc
+++ b/gcc/tree-ssa-loop-niter.cc
@@ -2238,6 +2238,8 @@ build_cltz_expr (tree src, bool leading, bool define_at_zero)
 			      build_int_cst (integer_type_node, prec));
 	}
     }
+  else if (fn == NULL_TREE)
+    return NULL_TREE;
   else if (prec == 2 * lli_prec)
     {
       tree src1 = fold_convert (long_long_unsigned_type_node,