--- a/pyqtgraph/Qt.py
+++ b/pyqtgraph/Qt.py
@@ -25,7 +25,7 @@
 ## This is done by first checking to see whether one of the libraries
 ## is already imported. If not, then attempt to import PyQt4, then PySide.
 if QT_LIB is None:
-    libOrder = [PYQT4, PYSIDE, PYQT5, PYSIDE2]
+    libOrder = [PYQT5]
 
     for lib in libOrder:
         if lib in sys.modules: