diff --git a/OpenCL/inc_cipher_serpent256.cl b/OpenCL/inc_cipher_serpent256.cl
index 462c0b9d0..6d2ec6d0b 100644
--- a/OpenCL/inc_cipher_serpent256.cl
+++ b/OpenCL/inc_cipher_serpent256.cl
@@ -401,7 +401,7 @@
     c = rotr32(c, 3);     \
     a = rotr32(a, 13)
 
-void serpent256_set_key (u32 *ks, const u32 *ukey)
+static void serpent256_set_key (u32 *ks, const u32 *ukey)
 {
   #ifdef _unroll
   #pragma unroll
@@ -457,7 +457,7 @@ void serpent256_set_key (u32 *ks, const u32 *ukey)
   k_set(32,a,b,c,d); sb3(a,b,c,d,e,f,g,h); k_get(32,e,f,g,h);
 }
 
-void serpent256_encrypt (const u32 *ks, const u32 *in, u32 *out)
+static void serpent256_encrypt (const u32 *ks, const u32 *in, u32 *out)
 {
   u32  a,b,c,d,e,f,g,h;
   u32  t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16;
@@ -507,7 +507,7 @@ void serpent256_encrypt (const u32 *ks, const u32 *in, u32 *out)
   out[3] = d;
 }
 
-void serpent256_decrypt (const u32 *ks, const u32 *in, u32 *out)
+static void serpent256_decrypt (const u32 *ks, const u32 *in, u32 *out)
 {
   u32  a,b,c,d,e,f,g,h;
   u32  t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16;
@@ -557,7 +557,7 @@ void serpent256_decrypt (const u32 *ks, const u32 *in, u32 *out)
   out[3] = d;
 }
 
-void serpent256_decrypt_xts (const u32 *ukey1, const u32 *ukey2, const u32 *in, u32 *out)
+static void serpent256_decrypt_xts (const u32 *ukey1, const u32 *ukey2, const u32 *in, u32 *out)
 {
   u32 T[4] = { 0 };
   u32 Z[4] = { 0 };