diff --git a/src/hash.c b/src/hash.c
index 1a9cd76..e02bdf1 100644
--- a/src/hash.c
+++ b/src/hash.c
@@ -63,7 +63,7 @@ nftp_crc(const uint8_t *data, size_t n)
 
 /* Refer. https://homes.cs.washington.edu/~suciu/XMLTK/xmill/www/XMILL/html/crc32_8c-source.html */
 /* This crc table is created with polynomial (0xedb88320L) */
-const uint32_t crc32_table[256] = {
+static const uint32_t crc32_table[256] = {
   0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
   0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
   0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,