diff --git a/modules/processing_class.py b/modules/processing_class.py
index 333e11925..24ec0d8d9 100644
--- a/modules/processing_class.py
+++ b/modules/processing_class.py
@@ -45,7 +45,7 @@ class StableDiffusionProcessing:
                  pag_scale: float = 0.0,
                  pag_adaptive: float = 0.5,
                  # styles
-                 styles: List[str] = None,
+                 styles: List[str] = [],
                  # vae
                  tiling: bool = False,
                  full_quality: bool = True,
@@ -119,7 +119,10 @@ class StableDiffusionProcessing:
                  # metadata
                  extra_generation_params: Dict[Any, Any] = {},
                 ):
+
+        # extra args set by processing loop
         self.task_args = {}
+
         # state items
         self.state: str = ''
         self.ops = []
@@ -136,6 +139,7 @@ class StableDiffusionProcessing:
         self.negative_pooleds = []
         self.disable_extra_networks = False
         self.iteration = 0
+
         # initializers
         self.prompt = prompt
         self.seed = seed
diff --git a/modules/styles.py b/modules/styles.py
index a5bfbecfd..0dd48eb7f 100644
--- a/modules/styles.py
+++ b/modules/styles.py
@@ -255,7 +255,7 @@ class StyleDatabase:
     def get_style_prompts(self, styles):
         if styles is None:
             return []
-        if styles is not isinstance(styles, list):
+        if not isinstance(styles, list):
             shared.log.error(f'Styles invalid: {styles}')
             return []
         return [self.find_style(x).prompt for x in styles]
@@ -263,7 +263,7 @@ class StyleDatabase:
     def get_negative_style_prompts(self, styles):
         if styles is None:
             return []
-        if styles is not isinstance(styles, list):
+        if not isinstance(styles, list):
             shared.log.error(f'Styles invalid: {styles}')
             return []
         return [self.find_style(x).negative_prompt for x in styles]
@@ -271,7 +271,7 @@ class StyleDatabase:
     def apply_styles_to_prompts(self, prompts, negatives, styles, seeds):
         if styles is None:
             return prompts, negatives
-        if styles is not isinstance(styles, list):
+        if not isinstance(styles, list):
             shared.log.error(f'Styles invalid styles: {styles}')
             return prompts, negatives
         if prompts is None or not isinstance(prompts, list):
@@ -294,7 +294,9 @@ class StyleDatabase:
         return parsed_positive, parsed_negative
 
     def apply_styles_to_prompt(self, prompt, styles):
-        if styles is None or not isinstance(styles, list):
+        if styles is None:
+            return prompt
+        if not isinstance(styles, list):
             shared.log.error(f'Styles invalid: {styles}')
             return prompt
         prompt = apply_styles_to_prompt(prompt, [self.find_style(x).prompt for x in styles])
@@ -302,7 +304,9 @@ class StyleDatabase:
         return prompt
 
     def apply_negative_styles_to_prompt(self, prompt, styles):
-        if styles is None or not isinstance(styles, list):
+        if styles is None:
+            return prompt
+        if not isinstance(styles, list):
             shared.log.error(f'Styles invalid: {styles}')
             return prompt
         prompt = apply_styles_to_prompt(prompt, [self.find_style(x).negative_prompt for x in styles])