diff --git a/SOPE/NGCards/ChangeLog b/SOPE/NGCards/ChangeLog
index fd6b23d98..b78570076 100644
--- a/SOPE/NGCards/ChangeLog
+++ b/SOPE/NGCards/ChangeLog
@@ -1,3 +1,8 @@
+2011-11-21  Francis Lachapelle  <flachapelle@inverse.ca>
+
+	* iCalTimeZone.m (+knownTimeZoneNames): ignore files that don't
+	have a .ics extension.
+
 2011-11-13  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
 
 	* iCalTrigger.m (-setValue:, value): removed useless accessors.
diff --git a/SOPE/NGCards/iCalTimeZone.m b/SOPE/NGCards/iCalTimeZone.m
index 9e645af09..4754c0793 100644
--- a/SOPE/NGCards/iCalTimeZone.m
+++ b/SOPE/NGCards/iCalTimeZone.m
@@ -148,8 +148,11 @@ static NSArray *knownTimeZones;
 		    if ([fm fileExistsAtPath: zonePath isDirectory: &b] && !b)
 		      {
 			ext = [zone rangeOfString: @".ics"];
-			zone = [zone substringToIndex: ext.location];
-			[timeZoneNames addObject: zone];
+                        if (ext.location != NSNotFound)
+                          {
+                            zone = [zone substringToIndex: ext.location];
+                            [timeZoneNames addObject: zone];
+                          }
 		      }
 		  }
 		}