diff --git a/vm_args.c b/vm_args.c
index c1d829c019..7a2f8135da 100644
--- a/vm_args.c
+++ b/vm_args.c
@@ -392,7 +392,7 @@ args_setup_kw_parameters_lookup(const ID key, VALUE *ptr, const VALUE *const pas
     return FALSE;
 }
 
-#define KW_SPECIFIED_BITS_MAX 32 /* TODO: 32 -> Fixnum's max bits */
+#define KW_SPECIFIED_BITS_MAX (32-1) /* TODO: 32 -> Fixnum's max bits */
 
 static void
 args_setup_kw_parameters(rb_execution_context_t *const ec, const rb_iseq_t *const iseq,
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 7480815d3a..1327050b2d 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -3026,7 +3026,7 @@ vm_check_keyword(lindex_t bits, lindex_t idx, const VALUE *ep)
     const VALUE kw_bits = *(ep - bits);
 
     if (FIXNUM_P(kw_bits)) {
-	int b = FIX2INT(kw_bits);
+	unsigned int b = (unsigned int)FIX2ULONG(kw_bits);
 	if ((idx < KW_SPECIFIED_BITS_MAX) && (b & (0x01 << idx)))
 	    return Qfalse;
     }