diff --git a/target/openrisc/sys_helper.c b/target/openrisc/sys_helper.c
index 541615bfb3..b66a45c1e0 100644
--- a/target/openrisc/sys_helper.c
+++ b/target/openrisc/sys_helper.c
@@ -142,7 +142,7 @@ void HELPER(mtspr)(CPUOpenRISCState *env, target_ulong spr, target_ulong rb)
         }
         break;
     case TO_SPR(9, 0):  /* PICMR */
-        env->picmr |= rb;
+        env->picmr = rb;
         break;
     case TO_SPR(9, 2):  /* PICSR */
         env->picsr &= ~rb;