diff --git a/OpenCL/m01730_a1.cl b/OpenCL/m01730_a1.cl
index fab4abb58..8b227e754 100644
--- a/OpenCL/m01730_a1.cl
+++ b/OpenCL/m01730_a1.cl
@@ -38,7 +38,7 @@ __constant u64 k_sha512[80] =
   SHA512C4c, SHA512C4d, SHA512C4e, SHA512C4f,
 };
 
-void sha512_transform (const u32x w0[4], const u32x w1[4], const u32x w2[4], const u32x w3[4], u64x digest[8])
+static void sha512_transform (const u32x w0[4], const u32x w1[4], const u32x w2[4], const u32x w3[4], u64x digest[8])
 {
   u64x w0_t = hl32_to_64 (w0[0], w0[1]);
   u64x w1_t = hl32_to_64 (w0[2], w0[3]);