diff --git a/python/taichi/lang/source_builder.py b/python/taichi/lang/source_builder.py
index ad465150cf2baa..744d070558f86b 100644
--- a/python/taichi/lang/source_builder.py
+++ b/python/taichi/lang/source_builder.py
@@ -16,8 +16,8 @@ def __init__(self, source, mode='bc'):
             self.compiled_file = os.path.join(self.td, 'source.bc')
             with open(self.source_file, 'w') as f:
                 f.write(source)
-            os.system('clang++-11 -flto -c ' + self.source_file +
-                      ' -o ' + self.compiled_file)
+            os.system('clang++-11 -flto -c ' + self.source_file + ' -o ' +
+                      self.compiled_file)
             self.bc = self.compiled_file
         elif self.mode == 'so':
             self.td = tempfile.mkdtemp()
@@ -25,8 +25,8 @@ def __init__(self, source, mode='bc'):
             self.compiled_file = os.path.join(self.td, 'source.so')
             with open(self.source_file, 'w') as f:
                 f.write(source)
-            os.system('g++ ' + self.source_file + ' -o ' +
-                      self.compiled_file + ' -fPIC -shared')
+            os.system('g++ ' + self.source_file + ' -o ' + self.compiled_file +
+                      ' -fPIC -shared')
             self.so = ctypes.CDLL(self.compiled_file)
         elif self.mode == 'asm':
             self.asm = source
diff --git a/taichi/codegen/codegen_llvm.cpp b/taichi/codegen/codegen_llvm.cpp
index b81bb3b29ebe7f..b506fec48b6568 100644
--- a/taichi/codegen/codegen_llvm.cpp
+++ b/taichi/codegen/codegen_llvm.cpp
@@ -2002,8 +2002,8 @@ void CodeGenLLVM::visit_call_bitcode(ExternalFuncCallStmt *stmt) {
   // Link external module to the core module
   if (linked_modules.find(stmt->bc_filename) == linked_modules.end()) {
     linked_modules.insert(stmt->bc_filename);
-    std::unique_ptr<llvm::Module> cpp_module = module_from_bitcode_file(
-        stmt->bc_filename, llvm_context);
+    std::unique_ptr<llvm::Module> cpp_module =
+        module_from_bitcode_file(stmt->bc_filename, llvm_context);
     auto *func_ptr = cpp_module->getFunction(stmt->bc_funcname);
     TI_ASSERT_INFO(func_ptr != nullptr, "{} is not founded in {}.",
                    stmt->bc_funcname, stmt->bc_filename);
diff --git a/tests/python/test_external_func.py b/tests/python/test_external_func.py
index c8f6e04b20093b..fe78f1625d134b 100644
--- a/tests/python/test_external_func.py
+++ b/tests/python/test_external_func.py
@@ -1,7 +1,8 @@
-import pytest
 import ctypes
 import os
 
+import pytest
+
 import taichi as ti
 
 
@@ -23,6 +24,7 @@ def test_source_builder_so():
     }
     '''
     sb_so = ti.SourceBuilder(source_so, 'so')
+
     @ti.kernel
     def func_so() -> ti.i32:
         a = 2.0
@@ -34,6 +36,7 @@ def func_so() -> ti.i32:
         p = 0
         sb_so.pow_int(args=(int(c + d), e), outputs=(p, ))
         return p
+
     assert func_so() == 11**8
 
 
@@ -55,6 +58,7 @@ def test_source_builder_bc():
     }
     '''
     sb_bc = ti.SourceBuilder(source_bc, 'bc')
+
     @ti.kernel
     def func_bc() -> ti.i32:
         a = 2.0
@@ -67,6 +71,7 @@ def func_bc() -> ti.i32:
         c_plus_d = int(c + d)
         sb_bc.pow_int(c_plus_d, e, p)
         return p
+
     assert func_bc() == 11**8
 
 
@@ -74,6 +79,7 @@ def func_bc() -> ti.i32:
 @ti.test(exclude=ti.cpu, require=ti.extension.extfunc)
 def test_source_builder_asm(x, y):
     sb = ti.SourceBuilder('$0 = %0 * %1', mode='asm')
+
     @ti.kernel
     def another_func(x: ti.f32, y: ti.f32) -> ti.f32:
         z = 0.0