diff --git a/changelog.d/12916.misc b/changelog.d/12916.misc
new file mode 100644
index 0000000000..347eb096db
--- /dev/null
+++ b/changelog.d/12916.misc
@@ -0,0 +1 @@
+Check if we are in a virtual environment before overriding the `PYTHONPATH` environment variable in the demo script.
diff --git a/demo/start.sh b/demo/start.sh
index 96b3a2ceab..fdd75816fb 100755
--- a/demo/start.sh
+++ b/demo/start.sh
@@ -6,11 +6,12 @@ CWD=$(pwd)
 
 cd "$DIR/.." || exit
 
-PYTHONPATH=$(readlink -f "$(pwd)")
-export PYTHONPATH
-
-
-echo "$PYTHONPATH"
+# Do not override PYTHONPATH if we are in a virtual env
+if [ "$VIRTUAL_ENV" = "" ]; then
+    PYTHONPATH=$(readlink -f "$(pwd)")
+    export PYTHONPATH
+	echo "$PYTHONPATH"
+fi
 
 # Create servers which listen on HTTP at 808x and HTTPS at 848x.
 for port in 8080 8081 8082; do