diff --git a/python/taichi/lang/expr.py b/python/taichi/lang/expr.py
index 4129786143ad6..05582cd6be9cb 100644
--- a/python/taichi/lang/expr.py
+++ b/python/taichi/lang/expr.py
@@ -74,7 +74,9 @@ def make_constant_expr(val, dtype):
         constant_dtype = impl.get_runtime(
         ).default_ip if dtype is None else dtype
         if constant_dtype not in integer_types:
-            raise TaichiTypeError('Integer literals must be annotated with a integer type. For type casting, use `ti.cast`.')
+            raise TaichiTypeError(
+                'Integer literals must be annotated with a integer type. For type casting, use `ti.cast`.'
+            )
         _check_in_range(to_numpy_type(constant_dtype), val)
         return Expr(
             _ti_core.make_const_expr_int(
@@ -83,7 +85,9 @@ def make_constant_expr(val, dtype):
         constant_dtype = impl.get_runtime(
         ).default_fp if dtype is None else dtype
         if constant_dtype not in real_types:
-            raise TaichiTypeError('Floating-point literals must be annotated with a floating-point type. For type casting, use `ti.cast`.')
+            raise TaichiTypeError(
+                'Floating-point literals must be annotated with a floating-point type. For type casting, use `ti.cast`.'
+            )
         return Expr(_ti_core.make_const_expr_fp(constant_dtype, val))
     raise TaichiTypeError(f'Invalid constant scalar data type: {type(val)}')
 
diff --git a/tests/python/test_literal.py b/tests/python/test_literal.py
index bc01753f3bbc9..88ac3827df213 100644
--- a/tests/python/test_literal.py
+++ b/tests/python/test_literal.py
@@ -62,7 +62,9 @@ def int_annotation_error():
 
     with pytest.raises(
             ti.TaichiTypeError,
-            match="Integer literals must be annotated with a integer type. For type casting, use `ti.cast`."):
+            match=
+            "Integer literals must be annotated with a integer type. For type casting, use `ti.cast`."
+    ):
         int_annotation_error()
 
 
@@ -74,5 +76,7 @@ def float_annotation_error():
 
     with pytest.raises(
             ti.TaichiTypeError,
-            match="Floating-point literals must be annotated with a floating-point type. For type casting, use `ti.cast`."):
+            match=
+            "Floating-point literals must be annotated with a floating-point type. For type casting, use `ti.cast`."
+    ):
         float_annotation_error()