diff --git a/plot/scripts/create-venv.sh b/plot/scripts/create-venv.sh
index a912fc839..a35252a17 100755
--- a/plot/scripts/create-venv.sh
+++ b/plot/scripts/create-venv.sh
@@ -21,6 +21,5 @@ fi
 
 "${python_bin}" -m venv "${VENV}"
 source "${VENV}/bin/activate"
-"${python_bin}" -m pip install cython
-"${python_bin}" -m pip install plotly numpy
+"${python_bin}" -m pip install cython plotly
 deactivate
diff --git a/plot/scripts/plotter.py b/plot/scripts/plotter.py
index a457d7922..04dcb672c 100644
--- a/plot/scripts/plotter.py
+++ b/plot/scripts/plotter.py
@@ -2,7 +2,6 @@
 import os
 import json
 import plotly.graph_objects as go
-import numpy as np
 
 
 def remove_key(d, key, empty_subkey=None):
@@ -113,7 +112,7 @@ def process_trace(trace):
 
     # Flatten 'z' when dealing with 3D scatters.
     if trace_type == 'scatter3d':
-        trace["z"] = np.array(trace["z"]).flatten()
+        trace["z"] = [item for sublist in trace["z"] for item in sublist]
 
     return map_trace_type_to_plotly_object(trace_type)(trace)