diff --git a/src/encauth/gcm/gcm_gf_mult.c b/src/encauth/gcm/gcm_gf_mult.c
index 37d8a57..e8d8c2d 100644
--- a/src/encauth/gcm/gcm_gf_mult.c
+++ b/src/encauth/gcm/gcm_gf_mult.c
@@ -83,7 +83,7 @@ static const unsigned char poly[] = { 0x00, 0xE1 };
 void gcm_gf_mult(const unsigned char *a, const unsigned char *b, unsigned char *c)
 {
    unsigned char Z[16], V[16];
-   unsigned x, y, z;
+   unsigned char x, y, z;
 
    zeromem(Z, 16);
    XMEMCPY(V, a, 16);