diff --git a/src/config.erl b/src/config.erl
index 98b5221..1a728b0 100644
--- a/src/config.erl
+++ b/src/config.erl
@@ -124,7 +124,7 @@
 
 get(Section) when is_binary(Section) ->
     ?MODULE:get(binary_to_list(Section));
-get(Section) ->
+get(Section) when is_list(Section) ->
     Matches = ets:match(?MODULE, {{Section, '$1'}, '$2'}),
     [{Key, Value} || [Key, Value] <- Matches].
 
@@ -133,7 +133,7 @@
 
 get(Section, Key, Default) when is_binary(Section) and is_binary(Key) ->
     ?MODULE:get(binary_to_list(Section), binary_to_list(Key), Default);
-get(Section, Key, Default) ->
+get(Section, Key, Default) when is_list(Section), is_list(Key) ->
     case ets:lookup(?MODULE, {Section, Key}) of
         [] -> Default;
         [{_, Match}] -> Match
@@ -149,7 +149,8 @@
 
 set(Sec, Key, Val, Persist, Reason) when is_binary(Sec) and is_binary(Key) ->
     ?MODULE:set(binary_to_list(Sec), binary_to_list(Key), Val, Persist, Reason);
-set(Section, Key, Value, Persist, Reason) ->
+set(Section, Key, Value, Persist, Reason)
+        when is_list(Section), is_list(Key), is_list(Value) ->
     gen_server:call(?MODULE, {set, Section, Key, Value, Persist, Reason}).
 
 
@@ -165,7 +166,7 @@
 
 delete(Sec, Key, Persist, Reason) when is_binary(Sec) and is_binary(Key) ->
     delete(binary_to_list(Sec), binary_to_list(Key), Persist, Reason);
-delete(Section, Key, Persist, Reason) ->
+delete(Section, Key, Persist, Reason) when is_list(Section), is_list(Key) ->
     gen_server:call(?MODULE, {delete, Section, Key, Persist, Reason}).