diff --git a/mongo_thingy/camelcase.py b/mongo_thingy/camelcase.py
index 73c2389..409685e 100644
--- a/mongo_thingy/camelcase.py
+++ b/mongo_thingy/camelcase.py
@@ -7,13 +7,13 @@
 
 
 def camelize(string):
-    if string.startswith("__"):
+    if string.startswith("__") or "_" not in string:
         return string
     return re.sub(CAMELIZE_RE, lambda m: m.group(1).upper(), string)
 
 
 def uncamelize(string):
-    if string.startswith("__"):
+    if string.startswith("__") or "_" in string:
         return string
     return re.sub(UNCAMELIZE_RE, r"_\g<0>", string).lower()