diff --git a/mace/kernels/opencl/cl/conv_2d_3x3.cl b/mace/kernels/opencl/cl/conv_2d_3x3.cl
index 30a5cdd7e5ea16b33a9bc6a58459b7f874e2e4ec..765582682a5261426a3c0a19292a5a5a2168775b 100644
--- a/mace/kernels/opencl/cl/conv_2d_3x3.cl
+++ b/mace/kernels/opencl/cl/conv_2d_3x3.cl
@@ -3,7 +3,7 @@
 __kernel void conv_2d_3x3(__read_only image2d_t input, /* [c%4 * w * c/4, h * b] */
                           __read_only image2d_t filter, /* cout%4 * cin * kw * kh, cout/4 */
 #ifdef BIAS
-    __read_only image2d_t bias, /* cout%4 * cout/4 */
+                          __read_only image2d_t bias, /* cout%4 * cout/4 */
 #endif
                           __write_only image2d_t output,
                           __private const int in_height,
@@ -35,11 +35,34 @@ __kernel void conv_2d_3x3(__read_only image2d_t input, /* [c%4 * w * c/4, h * b]
   out4 = out0;
 #endif
 
-  int w0 = out_w_blk - padding_left;
-  int w1 = w0 + out_w_blks;
-  int w2 = w1 + out_w_blks;
-  int w3 = w2 + out_w_blks;
-  int w4 = w3 + out_w_blks;
+#define DEFINE_IN_WIDTH(i) \
+  in_width##i[1] = in_width##i[0] + 1;                                                              \
+  in_width##i[2] = in_width##i[0] + 2;                                                              \
+  in_width##i[0] = (in_width##i[0] < 0 || in_width##i[0] >= in_width) ? (INT_MIN) : in_width##i[0]; \
+  in_width##i[1] = (in_width##i[1] < 0 || in_width##i[1] >= in_width) ? (INT_MIN) : in_width##i[1]; \
+  in_width##i[2] = (in_width##i[2] < 0 || in_width##i[2] >= in_width) ? (INT_MIN) : in_width##i[2];
+
+  int in_width0[3];
+  int in_width1[3];
+  int in_width2[3];
+  int in_width3[3];
+  int in_width4[3];
+  in_width0[0] = out_w_blk - padding_left;
+  in_width1[0] = in_width0[0] + out_w_blks;
+  in_width2[0] = in_width1[0] + out_w_blks;
+  in_width3[0] = in_width2[0] + out_w_blks;
+  in_width4[0] = in_width3[0] + out_w_blks;
+  DEFINE_IN_WIDTH(0);
+
+  DEFINE_IN_WIDTH(1);
+
+  DEFINE_IN_WIDTH(2);
+
+  DEFINE_IN_WIDTH(3);
+
+  DEFINE_IN_WIDTH(4);
+
+#undef DEFINE_IN_WIDTH
 
   const int batch_idx = out_hb / out_height;
   const int height_idx = out_hb % out_height;
@@ -64,37 +87,12 @@ __kernel void conv_2d_3x3(__read_only image2d_t input, /* [c%4 * w * c/4, h * b]
 
         in_idx = in_ch_blk * in_width;
 
-        in_width_idx = w0 + width_idx;
         // Judge the width border for padding input.
-        if (in_width_idx < 0 || in_width_idx >= in_width) {
-          in0 = 0;
-        } else {
-          in0 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width_idx, in_hb[hb_idx]));
-        }
-        in_width_idx = w1 + width_idx;
-        if (in_width_idx < 0 || in_width_idx >= in_width) {
-          in1 = 0;
-        } else {
-          in1 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width_idx, in_hb[hb_idx]));
-        }
-        in_width_idx = w2 + width_idx;
-        if (in_width_idx < 0 || in_width_idx >= in_width) {
-          in2 = 0;
-        } else {
-          in2 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width_idx, in_hb[hb_idx]));
-        }
-        in_width_idx = w3 + width_idx;
-        if (in_width_idx < 0 || in_width_idx >= in_width) {
-          in3 = 0;
-        } else {
-          in3 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width_idx, in_hb[hb_idx]));
-        }
-        in_width_idx = w4 + width_idx;
-        if (in_width_idx < 0 || in_width_idx >= in_width) {
-          in4 = 0;
-        } else {
-          in4 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width_idx, in_hb[hb_idx]));
-        }
+        in0 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width0[width_idx], in_hb[hb_idx]));
+        in1 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width1[width_idx], in_hb[hb_idx]));
+        in2 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width2[width_idx], in_hb[hb_idx]));
+        in3 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width3[width_idx], in_hb[hb_idx]));
+        in4 = READ_IMAGET(input, sampler, (int2)(in_idx + in_width4[width_idx], in_hb[hb_idx]));
 
         int filter_idx = (in_ch_blk << 2) + (hb_idx *  3 + width_idx) * rounded_in_ch;
         weights0 = READ_IMAGET(filter, sampler, (int2)(filter_idx + 0, out_ch_blk));
@@ -134,31 +132,32 @@ __kernel void conv_2d_3x3(__read_only image2d_t input, /* [c%4 * w * c/4, h * b]
   }
 
   const int out_x_base = out_ch_blk * out_width;
+  int w = out_w_blk;
   WRITE_IMAGET(output,
-               (int2)(out_x_base + w0 + padding_left, out_hb),
+               (int2)(out_x_base + w, out_hb),
                out0);
 
-  w1 += padding_left;
-  if (w1 >= out_width) return;
+  w += out_w_blks;
+  if (w >= out_width) return;
   WRITE_IMAGET(output,
-               (int2)(out_x_base + w1, out_hb),
+               (int2)(out_x_base + w, out_hb),
                out1);
 
-  w2 += padding_left;
-  if (w2 >= out_width) return;
+  w += out_w_blks;
+  if (w >= out_width) return;
   WRITE_IMAGET(output,
-               (int2)(out_x_base + w2, out_hb),
+               (int2)(out_x_base + w, out_hb),
                out2);
 
-  w3 += padding_left;
-  if (w3 >= out_width) return;
+  w += out_w_blks;
+  if (w >= out_width) return;
   WRITE_IMAGET(output,
-               (int2)(out_x_base + w3, out_hb),
+               (int2)(out_x_base + w, out_hb),
                out3);
 
-  w4 += padding_left;
-  if (w4 >= out_width) return;
+  w += out_w_blks;
+  if (w >= out_width) return;
   WRITE_IMAGET(output,
-               (int2)(out_x_base + w4, out_hb),
+               (int2)(out_x_base + w, out_hb),
                out4);
 }