diff --git a/def-helper.h b/def-helper.h
index b98ff69e4e..022a9ceb6a 100644
--- a/def-helper.h
+++ b/def-helper.h
@@ -128,6 +128,8 @@
 #define DEF_HELPER_5(name, ret, t1, t2, t3, t4, t5) \
     DEF_HELPER_FLAGS_5(name, 0, ret, t1, t2, t3, t4, t5)
 
+/* MAX_OPC_PARAM_IARGS must be set to n if last entry is DEF_HELPER_FLAGS_n. */
+
 #endif /* DEF_HELPER_H */
 
 #ifndef GEN_HELPER
diff --git a/exec-all.h b/exec-all.h
index c5ec8e1158..4f4fafc05a 100644
--- a/exec-all.h
+++ b/exec-all.h
@@ -51,7 +51,7 @@ typedef struct TranslationBlock TranslationBlock;
 #else
 #define MAX_OPC_PARAM_PER_ARG 1
 #endif
-#define MAX_OPC_PARAM_IARGS 4
+#define MAX_OPC_PARAM_IARGS 5
 #define MAX_OPC_PARAM_OARGS 1
 #define MAX_OPC_PARAM_ARGS (MAX_OPC_PARAM_IARGS + MAX_OPC_PARAM_OARGS)