diff --git a/core/views/caves.py b/core/views/caves.py
index 75b50a9..4af4217 100644
--- a/core/views/caves.py
+++ b/core/views/caves.py
@@ -169,12 +169,14 @@ def caveKey(c):
     if not c.kataster_number:
         return "9999." + c.unofficial_number
     else:
-        if int(c.kataster_number) >= 100:
-            return "99." + c.kataster_number
-        if int(c.kataster_number) >= 10:
-            return "9." + c.kataster_number
-        return c.kataster_number
-
+        try:
+            if int(c.kataster_number) >= 100:
+                return "99." + c.kataster_number
+            if int(c.kataster_number) >= 10:
+                return "9." + c.kataster_number
+            return c.kataster_number
+        except:
+            return c.kataster_number + "_ERROR"
 
 def getnotablecaves():
     notablecaves = []