diff --git a/mace/kernels/fully_connected.h b/mace/kernels/fully_connected.h
index a6fbebd61d95d29ec9a03eda08cfda06291ecd73..7a337a9d847ff658e4e48304122abe0ecd10e269 100644
--- a/mace/kernels/fully_connected.h
+++ b/mace/kernels/fully_connected.h
@@ -64,17 +64,20 @@ struct FullyConnectedFunctor<DeviceType::CPU, float>: FullyConnectedBase {
 
     Tensor::MappingGuard guard_input(input);
     Tensor::MappingGuard guard_weight(weight);
-    Tensor::MappingGuard guard_bias(bias);
     Tensor::MappingGuard guard_output(output);
     const float *input_ptr = input->data<float>();
     const float *weight_ptr = weight->data<float>();
-    const float *bias_ptr = bias == nullptr ? nullptr : bias->data<float>();
     float *output_ptr = output->mutable_data<float>();
 
     Gemv(weight_ptr, input_ptr, N, input_size, output_size, output_ptr);
-    for (int i = 0; i < N; ++i) {
-      for (int j = 0; j < output_size; ++j) {
-        output_ptr[j + i * output_size] += bias_ptr[j];
+
+    if (bias) {
+      Tensor::MappingGuard guard_bias(bias);
+      const float *bias_ptr = bias == nullptr ? nullptr : bias->data<float>();
+      for (int i = 0; i < N; ++i) {
+        for (int j = 0; j < output_size; ++j) {
+          output_ptr[j + i * output_size] += bias_ptr[j];
+        }
       }
     }
 
diff --git a/mace/ops/fully_connected.h b/mace/ops/fully_connected.h
index 286b22580ee6c8c42df61410748e607781522bb1..8ec0039185366a5419cf2b56dfd9317b3a5342a3 100644
--- a/mace/ops/fully_connected.h
+++ b/mace/ops/fully_connected.h
@@ -42,17 +42,23 @@ class FullyConnectedOp : public Operator<D, T> {
     if (D == DeviceType::CPU) {
       MACE_CHECK(
           input->dim(1) == weight->dim(1) && input->dim(2) == weight->dim(2) &&
-              input->dim(3) == weight->dim(3) && weight->dim(0) == bias->dim(0),
+              input->dim(3) == weight->dim(3),
           "The shape of Input: ", MakeString(input->shape()),
-          "The shape of Weight: ", MakeString(weight->shape()), " and Bias ",
-          bias->dim(0), " don't match.");
+          "The shape of Weight: ", MakeString(weight->shape()),
+          " don't match.");
     } else {
       MACE_CHECK(
           input->dim(1) == weight->dim(2) && input->dim(2) == weight->dim(3) &&
-              input->dim(3) == weight->dim(1) && weight->dim(0) == bias->dim(0),
+              input->dim(3) == weight->dim(1),
           "The shape of Input: ", MakeString(input->shape()),
-          "The shape of Weight: ", MakeString(weight->shape()), " and Bias ",
-          bias->dim(0), " don't match.");
+          "The shape of Weight: ", MakeString(weight->shape()),
+          " don't match.");
+    }
+    if (bias) {
+      MACE_CHECK(weight->dim(0) == bias->dim(0),
+                 "The shape of Weight: ", MakeString(weight->shape()),
+                 " and shape of Bias: ", bias->dim(0),
+                 " don't match.");
     }
 
     return functor_(input, weight, bias, output, future);