diff --git a/README.md b/README.md
index a0ae7d3..102fa92 100644
--- a/README.md
+++ b/README.md
@@ -104,7 +104,10 @@ crontab -e  # Remove the matrix64 line
 
 ## Manual Execution
 
+The script requires `samplebase.py` from the rpi-rgb-led-matrix library:
+
 ```bash
 cd /opt/matrix64
+export PYTHONPATH=/home/pi/rpi-rgb-led-matrix/bindings/python/samples
 sudo python3 matrix.py --led-rows=64 --led-cols=64
 ```
diff --git a/matrix64.service b/matrix64.service
index aaaa1f2..7cd3d35 100644
--- a/matrix64.service
+++ b/matrix64.service
@@ -7,6 +7,7 @@ Wants=network-online.target
 Type=simple
 User=root
 WorkingDirectory=/opt/matrix64
+Environment="PYTHONPATH=/home/pi/rpi-rgb-led-matrix/bindings/python/samples"
 ExecStart=/usr/bin/python3 /opt/matrix64/matrix.py --led-rows=64 --led-cols=64
 Restart=always
 RestartSec=10