diff --git a/scripts/mod_loader/modapi/personalities.lua b/scripts/mod_loader/modapi/personalities.lua
index 47946d2f..4fca0f81 100644
--- a/scripts/mod_loader/modapi/personalities.lua
+++ b/scripts/mod_loader/modapi/personalities.lua
@@ -29,6 +29,7 @@ local function dialogEvent(event, texts, overwrite)
 end
 
 local function addDialogTable(self, dialogTable, overwrite)
+	Assert.Equals('table', type(self), "Argument #0")
 	Assert.Equals('table', type(dialogTable), "Argument #1")
 
 	for event, texts in pairs(dialogTable) do
@@ -37,7 +38,8 @@ local function addDialogTable(self, dialogTable, overwrite)
 	end
 end
 
-local function addMissionDialogTable(missionId, dialogTable, overwrite)
+local function addMissionDialogTable(self, missionId, dialogTable, overwrite)
+	Assert.Equals('table', type(self), "Argument #0")
 	Assert.Equals('string', type(missionId), "Argument #1")
 	Assert.Equals('table', type(dialogTable), "Argument #2")