diff --git a/Compat/Compat.lua b/Compat/Compat.lua
index e78705a..4547a65 100644
--- a/Compat/Compat.lua
+++ b/Compat/Compat.lua
@@ -720,9 +720,18 @@ end
 
 -- Returns a list of quests the character has completed in its lifetime.
 -- https://wowpedia.fandom.com/wiki/API_GetQuestsCompleted
+local function ClearQuestCompleteTable(tbl)
+    if type(tbl) ~= "table" then return end
+    for key in pairs(tbl) do
+        tbl[key] = nil
+    end
+end
+
 function QuestieCompat.GetQuestsCompleted()
     if not Questie.db.char.complete then
         Questie.db.char.complete = {}
+    else
+        ClearQuestCompleteTable(Questie.db.char.complete)
     end
 
     QueryQuestsCompleted()
@@ -732,6 +741,10 @@ end
 -- Fires when the data requested by QueryQuestsCompleted() is available.
 -- https://wowpedia.fandom.com/wiki/QUEST_QUERY_COMPLETE
 function QuestieCompat:QUEST_QUERY_COMPLETE(event)
+    if not Questie.db.char.complete then
+        Questie.db.char.complete = {}
+    end
+    ClearQuestCompleteTable(Questie.db.char.complete)
     GetQuestsCompleted(Questie.db.char.complete)
 
     local questId = next(Questie.db.char.complete)
diff --git a/Tests/QuestieCompatCompletionRefresh_spec.lua b/Tests/QuestieCompatCompletionRefresh_spec.lua
new file mode 100644
index 0000000..459e67c
--- /dev/null
+++ b/Tests/QuestieCompatCompletionRefresh_spec.lua
@@ -0,0 +1,31 @@
+local function read(path)
+    local f = assert(io.open(path, "r"), "cannot open " .. path)
+    local content = f:read("*a")
+    f:close()
+    return content
+end
+
+describe("QuestieCompat completed quest refresh", function()
+    local compat = read("Compat/Compat.lua")
+
+    it("clears the completed-quest table before repopulating it", function()
+        local getQuestsStart = assert(compat:find("function QuestieCompat.GetQuestsCompleted()", 1, true))
+        local getQuestsEnd = assert(compat:find("-- Fires when the data requested by QueryQuestsCompleted() is available.", getQuestsStart, true))
+        local getQuests = compat:sub(getQuestsStart, getQuestsEnd)
+
+        local clearPos = assert(getQuests:find("ClearQuestCompleteTable(Questie.db.char.complete)", 1, true))
+        local queryPos = assert(getQuests:find("QueryQuestsCompleted()", 1, true))
+        assert.is_true(clearPos < queryPos)
+    end)
+
+    it("clears stale completions again when the server response arrives", function()
+        local eventStart = assert(compat:find("function QuestieCompat:QUEST_QUERY_COMPLETE(event)", 1, true))
+        local eventEnd = assert(compat:find("-- https://wowpedia.fandom.com/wiki/API_IsQuestFlaggedCompleted", eventStart, true))
+        local eventBlock = compat:sub(eventStart, eventEnd)
+
+        local clearPos = assert(eventBlock:find("ClearQuestCompleteTable(Questie.db.char.complete)", 1, true))
+        local fillPos = assert(eventBlock:find("GetQuestsCompleted(Questie.db.char.complete)", 1, true))
+
+        assert.is_true(clearPos < fillPos)
+    end)
+end)