diff --git a/target-sh4/helper.c b/target-sh4/helper.c
index f158b1f01d..6df6bde5a6 100644
--- a/target-sh4/helper.c
+++ b/target-sh4/helper.c
@@ -304,7 +304,7 @@ static void increment_urc(CPUState * env)
     urb = ((env->mmucr) >> 18) & 0x3f;
     urc = ((env->mmucr) >> 10) & 0x3f;
     urc++;
-    if (urc == urb || urc == UTLB_SIZE)
+    if (urc > urb || urc > (UTLB_SIZE - 1))
 	urc = 0;
     env->mmucr = (env->mmucr & 0xffff03ff) | (urc << 10);
 }