diff --git a/src/Selenium2Library/keywords/_selectelement.py b/src/Selenium2Library/keywords/_selectelement.py
index df6405211..261ead020 100644
--- a/src/Selenium2Library/keywords/_selectelement.py
+++ b/src/Selenium2Library/keywords/_selectelement.py
@@ -186,6 +186,8 @@ def select_from_list(self, locator, *items):
                 try: option_index = option_labels.index(item)
                 except: continue
             select_func(select, options, option_index)
+        if option_index is None:
+            raise ValueError("%s doesn't exist in list '%s'." % (items_str, locator))
 
     def unselect_from_list(self, locator, *items):
         """Unselects given values from select list identified by locator.
@@ -219,6 +221,8 @@ def unselect_from_list(self, locator, *items):
                 try: option_index = option_labels.index(item)
                 except: continue
             self._unselect_option_from_multi_select_list(select, options, option_index)
+        if option_index is None:
+            raise ValueError("%s doesn't exist in list '%s'." % (items_str, locator))
 
     # Private