diff --git a/README.md b/README.md
index 562d7b4..c9368db 100644
--- a/README.md
+++ b/README.md
@@ -11,9 +11,9 @@ DataFrames are optimized for simultaneous operations through [SIMD processing](h
 
 The following is a performance graph showing execution time using mesa and mesa-frames for the [Boltzmann Wealth model](https://mesa.readthedocs.io/en/stable/tutorials/intro_tutorial.html).
 
-![Performance Graph](https://github.com/adamamer20/mesa_frames/blob/main/docs/images/readme_plot_0.png)
+![Performance Graph](https://github.com/adamamer20/mesa_frames/blob/main/docs/general/images/readme_plot_0.png)
 
-![Performance Graph without Mesa](https://github.com/adamamer20/mesa_frames/blob/main/docs/images/readme_plot_1.png)
+![Performance Graph without Mesa](https://github.com/adamamer20/mesa_frames/blob/main/docs/general/images/readme_plot_1.png)
 
 (The script used to generate the graph can be found [here](https://github.com/adamamer20/mesa_frames/blob/main/docs/scripts/readme_plot.py), but if you want to additionally compare vs Mesa, you have to uncomment `mesa_implementation` and its label)
 
diff --git a/docs/images/readme_plot_0.png b/docs/general/images/readme_plot_0.png
similarity index 100%
rename from docs/images/readme_plot_0.png
rename to docs/general/images/readme_plot_0.png
diff --git a/docs/images/readme_plot_1.png b/docs/general/images/readme_plot_1.png
similarity index 100%
rename from docs/images/readme_plot_1.png
rename to docs/general/images/readme_plot_1.png
diff --git a/mesa_frames/concrete/pandas/mixin.py b/mesa_frames/concrete/pandas/mixin.py
index c6eeeff..7ac9cc5 100644
--- a/mesa_frames/concrete/pandas/mixin.py
+++ b/mesa_frames/concrete/pandas/mixin.py
@@ -316,7 +316,7 @@ def _prepare_df(df: pd.DataFrame, on: str | list[str] | None) -> pd.DataFrame:
             # Reset index if it is not used as a key to keep it in the DataFrame
             if df.index.name is not None or df.index.names[0] is not None:
                 df = df.reset_index()
-            df  = df.set_index(on)
+            df = df.set_index(on)
             return df
 
         left_index = False