diff --git a/OpenCL/m06100_a1.cl b/OpenCL/m06100_a1.cl
index 878058f38..c649d1a8a 100644
--- a/OpenCL/m06100_a1.cl
+++ b/OpenCL/m06100_a1.cl
@@ -1124,7 +1124,7 @@ __constant u32 rcl[R + 1] =
 
 // this is a highly optimized that assumes dgst[16] = { 0 }; only reuse of no 2nd transform is needed
 
-void whirlpool_transform (const u32x w[16], u32x dgst[16], __local u32 (*s_Ch)[256], __local u32 (*s_Cl)[256])
+static void whirlpool_transform (const u32x w[16], u32x dgst[16], __local u32 (*s_Ch)[256], __local u32 (*s_Cl)[256])
 {
   u32x Kh[8];
   u32x Kl[8];