diff --git a/Mapster/Config.lua b/Mapster/Config.lua
index 464d48b..e0da2d2 100644
--- a/Mapster/Config.lua
+++ b/Mapster/Config.lua
@@ -162,11 +162,17 @@ local function getOptions()
 	return options
 end
 
-local function optFunc() 
-	-- open the profiles tab before, so the menu expands
-	InterfaceOptionsFrame_OpenToCategory(Mapster.optionsFrames.Profiles)
-	InterfaceOptionsFrame_OpenToCategory(Mapster.optionsFrames.Mapster)
-	InterfaceOptionsFrame:Raise()
+local function optFunc()
+	-- CoA: InterfaceOptionsFrame_OpenToCategory / InterfaceOptionsFrame are nil on 3.3.5;
+	-- fall back to AceConfigDialog which works on all clients.
+	if InterfaceOptionsFrame_OpenToCategory then
+		-- open the profiles tab before, so the menu expands
+		InterfaceOptionsFrame_OpenToCategory(Mapster.optionsFrames.Profiles)
+		InterfaceOptionsFrame_OpenToCategory(Mapster.optionsFrames.Mapster)
+		if InterfaceOptionsFrame then InterfaceOptionsFrame:Raise() end
+	else
+		LibStub("AceConfigDialog-3.0"):Open("Mapster")
+	end
 end
 
 function Mapster:SetupOptions()