diff --git a/hls4ml/utils/plot.py b/hls4ml/utils/plot.py
index fb435bcbe7..3a49599052 100644
--- a/hls4ml/utils/plot.py
+++ b/hls4ml/utils/plot.py
@@ -77,7 +77,7 @@ def model_to_dot(
     layers = model.get_layers()
 
     # Create graph nodes.
-    for i, layer in enumerate(layers):
+    for layer in layers:
         # layer_id = str(id(layer))
         layer_id = str(layer.index)
 
@@ -112,8 +112,8 @@ def format_shape(shape):
             if class_name != 'Input':
                 if len(layer.inputs) > 1:
                     input_shapes = []
-                    for i in layer.inputs:
-                        input_layer = layer.get_input_variable(i)
+                    for input_name in layer.inputs:
+                        input_layer = layer.get_input_variable(input_name)
                         if input_layer is not None:
                             input_shapes.append(input_layer.shape)
                         else:
diff --git a/hls4ml/writer/catapult_writer.py b/hls4ml/writer/catapult_writer.py
index ba7e511995..1f12e789f8 100755
--- a/hls4ml/writer/catapult_writer.py
+++ b/hls4ml/writer/catapult_writer.py
@@ -342,8 +342,8 @@ def write_project_cpp(self, model):
                             newline += '    ' + func[0] + ' // ' + layer.name + '\n'
                         else:
                             newline += '    // ' + layer.name + '\n'
-                            for line in func:
-                                newline += '    ' + line + '\n'
+                            for func_line in func:
+                                newline += '    ' + func_line + '\n'
                         if model.config.trace_output and layer.get_attr('trace', False):
                             newline += '#ifndef __SYNTHESIS__\n'
                             for var in vars:
diff --git a/hls4ml/writer/coyote_writer.py b/hls4ml/writer/coyote_writer.py
index ab97c2477c..38ef1b5cb4 100644
--- a/hls4ml/writer/coyote_writer.py
+++ b/hls4ml/writer/coyote_writer.py
@@ -163,8 +163,8 @@ def write_project_cpp(self, model):
                             newline += '    ' + func[0] + ' // ' + layer.name + '\n'
                         else:
                             newline += '    // ' + layer.name + '\n'
-                            for line in func:
-                                newline += '    ' + line + '\n'
+                            for func_line in func:
+                                newline += '    ' + func_line + '\n'
                         if model.config.trace_output and layer.get_attr('trace', False):
                             vars = layer.get_variables()
                             newline += '#ifndef __SYNTHESIS__\n'
diff --git a/hls4ml/writer/libero_writer.py b/hls4ml/writer/libero_writer.py
index a5be68c81e..f49fe9bb9f 100644
--- a/hls4ml/writer/libero_writer.py
+++ b/hls4ml/writer/libero_writer.py
@@ -271,8 +271,8 @@ def write_project_cpp(self, model):
                                 newline += '    ' + func[0] + ' // ' + layer.name + '\n'
                             else:
                                 newline += '    // ' + layer.name + '\n'
-                                for line in func:
-                                    newline += '    ' + line + '\n'
+                                for func_line in func:
+                                    newline += '    ' + func_line + '\n'
                             if model.config.trace_output and layer.get_attr('trace', False):
                                 newline += '#ifndef __SYNTHESIS__\n'
                                 for var in vars:
diff --git a/hls4ml/writer/vivado_writer.py b/hls4ml/writer/vivado_writer.py
index 0642462a7f..eb791cd9ae 100644
--- a/hls4ml/writer/vivado_writer.py
+++ b/hls4ml/writer/vivado_writer.py
@@ -252,8 +252,8 @@ def write_project_cpp(self, model):
                             newline += '    ' + func[0] + ' // ' + layer.name + '\n'
                         else:
                             newline += '    // ' + layer.name + '\n'
-                            for line in func:
-                                newline += '    ' + line + '\n'
+                            for func_line in func:
+                                newline += '    ' + func_line + '\n'
                         if model.config.trace_output and layer.get_attr('trace', False):
                             vars = layer.get_variables()
                             newline += '#ifndef __SYNTHESIS__\n'