diff --git a/tools/Python/mcplot/pyqtgraph/mcplot.in b/tools/Python/mcplot/pyqtgraph/mcplot.in
index ae4654e66..bbb3254b5 100755
--- a/tools/Python/mcplot/pyqtgraph/mcplot.in
+++ b/tools/Python/mcplot/pyqtgraph/mcplot.in
@@ -24,6 +24,12 @@ canrun() {
         cmd="${cmd}import ${name}; "
     done
     python3 -c "${cmd}"
+
+    python3 -c "import PySide6"
+    if [ $? == 0 ]; then
+	mcstas_errmsg Your Python has PySide6 - ${TOOL} will not function correctly. Please run in an environment with PyQt5 only.
+	exit 127;
+    fi
 }
 
 if ( canrun ); then