diff --git a/OpenCL/m18100_a0-pure.cl b/OpenCL/m18100_a0-pure.cl
index 20b1dc5af..7903b9cb3 100644
--- a/OpenCL/m18100_a0-pure.cl
+++ b/OpenCL/m18100_a0-pure.cl
@@ -60,7 +60,7 @@ __kernel void m18100_mxx (__global pw_t *pws, __constant const kernel_rule_t *ru
     sha1_hmac_final (&ctx);
 
     // calculate the offset using the least 4 bits of the last byte of our hash
-    const int otp_offset = ctx.opad.h[4] & 0xf;
+    const int otp_offset = (int) ctx.opad.h[4] & 0xf;
 
     // initialize a buffer for the otp code
     unsigned int otp_code = 0;
@@ -153,7 +153,7 @@ __kernel void m18100_sxx (__global pw_t *pws, __constant const kernel_rule_t *ru
     sha1_hmac_final (&ctx);
 
     // calculate the offset using the least 4 bits of the last byte of our hash
-    const int otp_offset = ctx.opad.h[4] & 0xf;
+    const int otp_offset = (int) ctx.opad.h[4] & 0xf;
 
     // initialize a buffer for the otp code
     unsigned int otp_code = 0;
diff --git a/OpenCL/m18100_a1-pure.cl b/OpenCL/m18100_a1-pure.cl
index d82915ac5..d03f1a459 100644
--- a/OpenCL/m18100_a1-pure.cl
+++ b/OpenCL/m18100_a1-pure.cl
@@ -83,7 +83,7 @@ __kernel void m18100_mxx (__global pw_t *pws, __global const kernel_rule_t *rule
     sha1_hmac_final (&ctx);
 
     // calculate the offset using the least 4 bits of the last byte of our hash
-    const int otp_offset = ctx.opad.h[4] & 0xf;
+    const int otp_offset = (int) ctx.opad.h[4] & 0xf;
 
     // initialize a buffer for the otp code
     unsigned int otp_code = 0;
@@ -201,7 +201,7 @@ __kernel void m18100_sxx (__global pw_t *pws, __global const kernel_rule_t *rule
     sha1_hmac_final (&ctx);
 
     // calculate the offset using the least 4 bits of the last byte of our hash
-    const int otp_offset = ctx.opad.h[4] & 0xf;
+    const int otp_offset = (int) ctx.opad.h[4] & 0xf;
 
     // initialize a buffer for the otp code
     unsigned int otp_code = 0;
diff --git a/OpenCL/m18100_a3-pure.cl b/OpenCL/m18100_a3-pure.cl
index b80ac8dce..22083acf8 100644
--- a/OpenCL/m18100_a3-pure.cl
+++ b/OpenCL/m18100_a3-pure.cl
@@ -69,7 +69,7 @@ __kernel void m18100_mxx (__global pw_t *pws, __global const kernel_rule_t *rule
     sha1_hmac_final_vector (&ctx);
 
     // calculate the offset using the least 4 bits of the last byte of our hash
-    const int otp_offset = ctx.opad.h[4] & 0xf;
+    const int otp_offset = (int) ctx.opad.h[4] & 0xf;
 
     // initialize a buffer for the otp code
     unsigned int otp_code = 0;
@@ -173,7 +173,7 @@ __kernel void m18100_sxx (__global pw_t *pws, __global const kernel_rule_t *rule
     sha1_hmac_final_vector (&ctx);
 
     // calculate the offset using the least 4 bits of the last byte of our hash
-    const int otp_offset = ctx.opad.h[4] & 0xf;
+    const int otp_offset = (int) ctx.opad.h[4] & 0xf;
 
     // initialize a buffer for the otp code
     unsigned int otp_code = 0;