diff --git a/src/opr/impl/dnn/batch_norm.cpp b/src/opr/impl/dnn/batch_norm.cpp
index 73fd6956bcbe6fecf41a1adb84b7b374b797800d..4cd502d25f64562f32c197d7d49ce8f15e11ec0b 100644
--- a/src/opr/impl/dnn/batch_norm.cpp
+++ b/src/opr/impl/dnn/batch_norm.cpp
@@ -50,8 +50,8 @@ BatchNormForward::BatchNormForward(VarNode *x,
             mgb_throw_if(!(dest_opr->same_type<SharedDeviceTensor>() ||
                     dest_opr->same_type<VolatileSharedDeviceTensor>()),
                     GraphError,
-                    "mean and variance in training mode BatchNorm must be",
-                    "SharedDeviceTensor or VolatileSharedDeviceTensor;",
+                    "mean and variance in training mode BatchNorm must be"
+                    "SharedDeviceTensor or VolatileSharedDeviceTensor;"
                     "got %s{%s} actually",
                     dest_opr->cname(), dest_opr->dyn_typeinfo()->name);
         };