diff --git a/pystencils/backends/cbackend.py b/pystencils/backends/cbackend.py
index 9f576b4aa01cb2ec3f76ece029c6daaa5faeeaf1..aca5e5da1e36774dbd7b69b1a0f0f57012bc4dd6 100644
--- a/pystencils/backends/cbackend.py
+++ b/pystencils/backends/cbackend.py
@@ -298,7 +298,7 @@ class CBackend:
         return node.get_code(self._dialect, self._vector_instruction_set)
 
     def _print_SourceCodeComment(self, node):
-        return "/* " + node.text + " */"
+        return f"/* {node.text } */"
 
     def _print_EmptyLine(self, node):
         return ""
@@ -316,7 +316,7 @@ class CBackend:
         result = f"if ({condition_expr})\n{true_block} "
         if node.false_block:
             false_block = self._print_Block(node.false_block)
-            result += "else " + false_block
+            result += f"else {false_block}"
         return result
 
 
@@ -336,7 +336,7 @@ class CustomSympyPrinter(CCodePrinter):
             return self._typed_number(expr.evalf(), get_type_of_expression(expr))
 
         if expr.exp.is_integer and expr.exp.is_number and 0 < expr.exp < 8:
-            return "(" + self._print(sp.Mul(*[expr.base] * expr.exp, evaluate=False)) + ")"
+            return f"({self._print(sp.Mul(*[expr.base] * expr.exp, evaluate=False))})"
         elif expr.exp.is_integer and expr.exp.is_number and - 8 < expr.exp < 0:
             return f"1 / ({self._print(sp.Mul(*([expr.base] * -expr.exp), evaluate=False))})"
         else:
diff --git a/pystencils/backends/cuda_backend.py b/pystencils/backends/cuda_backend.py
index b43cfb4ededa3ea5c84ff2eef9d434d602f358b2..2d7dc579e932aee814e5207801971246122a9a88 100644
--- a/pystencils/backends/cuda_backend.py
+++ b/pystencils/backends/cuda_backend.py
@@ -104,7 +104,6 @@ class CudaSympyPrinter(CustomSympyPrinter):
             assert len(expr.args) == 1, f"__fsqrt_rn has one argument, but {len(expr.args)} where given"
             return f"__fsqrt_rn({self._print(expr.args[0])})"
         elif isinstance(expr, fast_inv_sqrt):
-            print(len(expr.args) == 1)
             assert len(expr.args) == 1, f"__frsqrt_rn has one argument, but {len(expr.args)} where given"
             return f"__frsqrt_rn({self._print(expr.args[0])})"
         return super()._print_Function(expr)
diff --git a/pystencils_tests/test_fast_approximation.py b/pystencils_tests/test_fast_approximation.py
index f4d19fa19fa615aaa76a7b1bb445fa7bdb886237..ccd2d7b8ea15a4c36069a58bc1197b314cce2ca1 100644
--- a/pystencils_tests/test_fast_approximation.py
+++ b/pystencils_tests/test_fast_approximation.py
@@ -11,9 +11,9 @@ def test_fast_sqrt():
 
     assert len(insert_fast_sqrts(expr).atoms(fast_sqrt)) == 1
     assert len(insert_fast_sqrts([expr])[0].atoms(fast_sqrt)) == 1
-    ast = ps.create_kernel(ps.Assignment(g[0, 0], insert_fast_sqrts(expr)), target='gpu')
-    ast.compile()
-    code_str = ps.get_code_str(ast)
+    ast_gpu = ps.create_kernel(ps.Assignment(g[0, 0], insert_fast_sqrts(expr)), target='gpu')
+    ast_gpu.compile()
+    code_str = ps.get_code_str(ast_gpu)
     assert '__fsqrt_rn' in code_str
 
     expr = ps.Assignment(sp.Symbol("tmp"), 3 / sp.sqrt(f[0, 0] + f[1, 0]))
@@ -21,9 +21,9 @@ def test_fast_sqrt():
 
     ac = ps.AssignmentCollection([expr], [])
     assert len(insert_fast_sqrts(ac).main_assignments[0].atoms(fast_inv_sqrt)) == 1
-    ast = ps.create_kernel(insert_fast_sqrts(ac), target='gpu')
-    ast.compile()
-    code_str = ps.get_code_str(ast)
+    ast_gpu = ps.create_kernel(insert_fast_sqrts(ac), target='gpu')
+    ast_gpu.compile()
+    code_str = ps.get_code_str(ast_gpu)
     assert '__frsqrt_rn' in code_str