diff --git a/dnn/src/fallback/conv_bias/common.h b/dnn/src/fallback/conv_bias/common.h
index aac5ce72c7d4871e343ea405d7d2f81de5ce060b..29fdae8c08c8e92e1c17b63caa21eec92f57fd73 100644
--- a/dnn/src/fallback/conv_bias/common.h
+++ b/dnn/src/fallback/conv_bias/common.h
@@ -122,6 +122,22 @@ using BiasMode = ConvBiasForward::BiasMode;
             break;                            \
     }
 
+#define DISPATCH_FILTER_CHANNEL_WISE(filter, kern, arg...) \
+    switch (filter) {                                      \
+        case 2:                                            \
+            kern(2, ##arg);                                \
+            break;                                         \
+        case 3:                                            \
+            kern(3, ##arg);                                \
+            break;                                         \
+        case 5:                                            \
+            kern(5, ##arg);                                \
+            break;                                         \
+        default:                                           \
+            megdnn_assert(0);                              \
+            break;                                         \
+    }
+
 enum class PostprocessMode : uint8_t {
     FLOAT = 0,  ///< support all biasmode and no_nonlinemode
     NO_PROCESS, ///<support  non bias and identity