diff --git a/docs/examples/04_modifying_layermodels.ipynb b/docs/examples/04_modifying_layermodels.ipynb
index 9233c982..322c433b 100644
--- a/docs/examples/04_modifying_layermodels.ipynb
+++ b/docs/examples/04_modifying_layermodels.ipynb
@@ -263,24 +263,6 @@
     "split_reindexer"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "The new layers are named according to the REGIS codes, with an added number if the layer was split into multiple sub-layers. For plotting a cross-section we want to use the original color from the REGIS cross-section plot for the new sub-layers."
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "for j, i in split_reindexer.items():\n",
-    "    if j not in colors:\n",
-    "        colors[j] = colors[i]"
-   ]
-  },
   {
    "cell_type": "markdown",
    "metadata": {},
diff --git a/nlmod/dims/layers.py b/nlmod/dims/layers.py
index c468582f..d4c0eacf 100644
--- a/nlmod/dims/layers.py
+++ b/nlmod/dims/layers.py
@@ -263,7 +263,7 @@ def split_layers_ds(
     for lay0 in split_dict:
         for i, _ in enumerate(split_dict[lay0]):
             index = layers.index(lay0)
-            layers.insert(index, lay0 + "_" + str(i + 1))
+            layers.insert(index, lay0 + "_" + str(i))
             layers_org.insert(index, lay0)
     ds = ds.reindex({"layer": layers})
 
@@ -300,7 +300,7 @@ def split_layers_ds(
 def _split_var(ds, var, layer, thickness, fctrs, top, bot):
     """Internal method to split a variable of one layer in multiple layers."""
     for i in range(len(fctrs)):
-        name = layer + "_" + str(i + 1)
+        name = layer + "_" + str(i)
         if var == top:
             # take orignal top and subtract thickness of higher splitted layers
             ds[var].loc[name] = ds[var].loc[layer] - np.sum(fctrs[:i]) * thickness
diff --git a/nlmod/plot/dcs.py b/nlmod/plot/dcs.py
index 0a879445..67a02ded 100644
--- a/nlmod/plot/dcs.py
+++ b/nlmod/plot/dcs.py
@@ -181,7 +181,8 @@ def plot_layers(
         if isinstance(colors, pd.DataFrame):
             colors = colors["color"]
         if isinstance(colors, (dict, pd.Series)):
-            colors = [colors[layer] for layer in self.layer]
+            # split on _ in case layers were split and appended with a numbered suffix
+            colors = [colors[layer.split("_")[0]] for layer in self.layer]
 
         if colors == "none":
             colors = ["none"] * len(self.layer)