diff --git a/include/exec/helper-tcg.h b/include/exec/helper-tcg.h
index 0da6b97..d704c81 100644
--- a/include/exec/helper-tcg.h
+++ b/include/exec/helper-tcg.h
@@ -6,22 +6,34 @@
 
 #include <exec/helper-head.h>
 
-#define DEF_HELPER_FLAGS_0(name, flags, ret)  { HELPER(name), #name },
+#define DEF_HELPER_FLAGS_0(NAME, FLAGS, ret) \
+  { .func = HELPER(NAME), .name = #NAME, .flags = FLAGS, \
+    .sizemask = dh_sizemask(ret, 0) },
 
-#define DEF_HELPER_FLAGS_1(name, flags, ret, t1) \
-DEF_HELPER_FLAGS_0(name, flags, ret)
+#define DEF_HELPER_FLAGS_1(NAME, FLAGS, ret, t1) \
+  { .func = HELPER(NAME), .name = #NAME, .flags = FLAGS, \
+    .sizemask = dh_sizemask(ret, 0) | dh_sizemask(t1, 1) },
 
-#define DEF_HELPER_FLAGS_2(name, flags, ret, t1, t2) \
-DEF_HELPER_FLAGS_0(name, flags, ret)
+#define DEF_HELPER_FLAGS_2(NAME, FLAGS, ret, t1, t2) \
+  { .func = HELPER(NAME), .name = #NAME, .flags = FLAGS, \
+    .sizemask = dh_sizemask(ret, 0) | dh_sizemask(t1, 1) \
+    | dh_sizemask(t2, 2) },
 
-#define DEF_HELPER_FLAGS_3(name, flags, ret, t1, t2, t3) \
-DEF_HELPER_FLAGS_0(name, flags, ret)
+#define DEF_HELPER_FLAGS_3(NAME, FLAGS, ret, t1, t2, t3) \
+  { .func = HELPER(NAME), .name = #NAME, .flags = FLAGS, \
+    .sizemask = dh_sizemask(ret, 0) | dh_sizemask(t1, 1) \
+    | dh_sizemask(t2, 2) | dh_sizemask(t3, 3) },
 
-#define DEF_HELPER_FLAGS_4(name, flags, ret, t1, t2, t3, t4) \
-DEF_HELPER_FLAGS_0(name, flags, ret)
+#define DEF_HELPER_FLAGS_4(NAME, FLAGS, ret, t1, t2, t3, t4) \
+  { .func = HELPER(NAME), .name = #NAME, .flags = FLAGS, \
+    .sizemask = dh_sizemask(ret, 0) | dh_sizemask(t1, 1) \
+    | dh_sizemask(t2, 2) | dh_sizemask(t3, 3) | dh_sizemask(t4, 4) },
 
-#define DEF_HELPER_FLAGS_5(name, flags, ret, t1, t2, t3, t4, t5) \
-DEF_HELPER_FLAGS_0(name, flags, ret)
+#define DEF_HELPER_FLAGS_5(NAME, FLAGS, ret, t1, t2, t3, t4, t5) \
+  { .func = HELPER(NAME), .name = #NAME, .flags = FLAGS, \
+    .sizemask = dh_sizemask(ret, 0) | dh_sizemask(t1, 1) \
+    | dh_sizemask(t2, 2) | dh_sizemask(t3, 3) | dh_sizemask(t4, 4) \
+    | dh_sizemask(t5, 5) },
 
 #include "helper.h"
 #include "tcg-runtime.h"
diff --git a/tcg/tcg.c b/tcg/tcg.c
index 56ef0fd..004f4bf 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -310,6 +310,8 @@
 typedef struct TCGHelperInfo {
     void *func;
     const char *name;
+    unsigned flags;
+    unsigned sizemask;
 } TCGHelperInfo;
 
 #include "exec/helper-proto.h"
@@ -696,6 +698,11 @@
     int real_args;
     int nb_rets;
     TCGArg *nparam;
+    TCGHelperInfo *info;
+
+    info = g_hash_table_lookup(s->helpers, (gpointer)func);
+    assert(info != NULL);
+    assert(info->sizemask == sizemask);
 
 #if defined(__sparc__) && !defined(__arch64__) \
     && !defined(CONFIG_TCG_INTERPRETER)