diff --git a/target-alpha/helper.c b/target-alpha/helper.c
index 46335cdf9c..9a039cb96b 100644
--- a/target-alpha/helper.c
+++ b/target-alpha/helper.c
@@ -466,6 +466,7 @@ int cpu_alpha_mtpr (CPUState *env, int iprn, uint64_t val, uint64_t *oldvalp)
             env->ipr[IPR_SYSPTBR] = val;
         else
             ret = -1;
+        break;
     case IPR_TBCHK:
         /* Read-only */
         ret = -1;