1 files changed, 4 insertions, 0 deletions

diff --git a/src/lj_ccallback.c b/src/lj_ccallback.c
index 724dea607..2ed84507a 100644
--- a/src/lj_ccallback.c
+++ b/src/lj_ccallback.c
@@ -704,6 +704,10 @@ static void callback_conv_result(CTState *cts, lua_State *L, TValue *o)
     if (ctr->size <= 4 &&
         (LJ_ABI_SOFTFP || ctype_isinteger_or_bool(ctr->info)))
       *(int64_t *)dp = (int64_t)*(int32_t *)dp;
+#elif LJ_TARGET_X64
+    /* Always zero-extend results to 64 bits. */
+    if (ctr->size <= 4 && ctype_isinteger_or_bool(ctr->info))
+      *(uint64_t *)dp = (uint64_t)*(uint32_t *)dp;
 #endif
 #if LJ_TARGET_X86
     if (ctype_isfp(ctr->info))