diff --git a/direct/src/gui/DirectScrollBar.py b/direct/src/gui/DirectScrollBar.py
index 746a5d0fd7..819ee1d1d9 100644
--- a/direct/src/gui/DirectScrollBar.py
+++ b/direct/src/gui/DirectScrollBar.py
@@ -106,8 +106,10 @@ class DirectScrollBar(DirectFrame):
     def setOrientation(self):
         if self['orientation'] == HORIZONTAL:
             self.guiItem.setAxis(Vec3(1, 0, 0))
-        else:
+        elif self['orientation'] == VERTICAL:
             self.guiItem.setAxis(Vec3(0, 0, -1))
+        else:
+            raise ValueError, 'Invalid value for orientation: %s' % (self['orientation'])
 
     def setManageButtons(self):
         self.guiItem.setManagePieces(self['manageButtons'])
diff --git a/direct/src/gui/DirectSlider.py b/direct/src/gui/DirectSlider.py
index 8891242dfe..e0d2332d06 100644
--- a/direct/src/gui/DirectSlider.py
+++ b/direct/src/gui/DirectSlider.py
@@ -99,8 +99,10 @@ class DirectSlider(DirectFrame):
     def setOrientation(self):
         if self['orientation'] == HORIZONTAL:
             self.guiItem.setAxis(Vec3(1, 0, 0))
-        else:
+        elif self['orientation'] == VERTICAL:
             self.guiItem.setAxis(Vec3(0, 0, 1))
+        else:
+            raise ValueError, 'Invalid value for orientation: %s' % (self['orientation'])
 
     def destroy(self):
         DirectFrame.destroy(self)