diff --git a/src/dump.c b/src/dump.c
index 09857e8c5..24ddd90b8 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -1045,7 +1045,7 @@ is_valid_c_symbol_name(const char *name)
    return TRUE;
 }
 
-static int
+static mrb_bool
 dump_bigendian_p(uint8_t flags)
 {
   switch (flags & DUMP_ENDIAN_NAT) {