diff --git a/Source/CMakeLists.txt b/Source/CMakeLists.txt
index 187754ba7..5392f9ed6 100644
--- a/Source/CMakeLists.txt
+++ b/Source/CMakeLists.txt
@@ -152,6 +152,8 @@ set(libdevilutionx_SRCS
   qol/stash.cpp
   qol/xpbar.cpp
 
+  quests/validation.cpp
+
   storm/storm_net.cpp
   storm/storm_svid.cpp
 
diff --git a/Source/msg.cpp b/Source/msg.cpp
index 9893f3c24..f462c4e4a 100644
--- a/Source/msg.cpp
+++ b/Source/msg.cpp
@@ -40,6 +40,7 @@
 #include "pfile.h"
 #include "plrmsg.h"
 #include "portals/validation.hpp"
+#include "quests/validation.hpp"
 #include "spells.h"
 #include "storm/storm_net.hpp"
 #include "sync.h"
@@ -296,6 +297,11 @@ bool IsPortalDeltaValid(const DPortal &portal)
 	return IsPortalDeltaValid(position, portal.level, portal.ltype, portal.setlvl);
 }
 
+bool IsQuestDeltaValid(quest_id qidx, const MultiQuests &quest)
+{
+	return IsQuestDeltaValid(qidx, quest.qstate, quest.qlog, quest.qmsg);
+}
+
 uint8_t GetLevelForMultiplayer(uint8_t level, bool isSetLevel)
 {
 	if (isSetLevel)
@@ -711,6 +717,9 @@ const std::byte *DeltaImportJunk(const std::byte *src, const std::byte *end)
 			return nullptr;
 		}
 		memcpy(&sgJunk.quests[q], src, sizeof(MultiQuests));
+		if (!IsQuestDeltaValid(static_cast<quest_id>(qidx), sgJunk.quests[q])) {
+			sgJunk.quests[q].qstate = QUEST_INVALID;
+		}
 		src += sizeof(MultiQuests);
 		q++;
 	}
diff --git a/Source/quests/validation.cpp b/Source/quests/validation.cpp
new file mode 100644
index 000000000..fff38ac01
--- /dev/null
+++ b/Source/quests/validation.cpp
@@ -0,0 +1,46 @@
+/**
+ * @file quests/validation.cpp
+ *
+ * Implementation of functions for validation of quest data.
+ */
+
+#include "quests/validation.hpp"
+
+#include <cstdint>
+
+#include "objdat.h"
+#include "quests.h"
+#include "textdat.h"
+#include "utils/is_of.hpp"
+
+namespace devilution {
+
+bool IsQuestDeltaValid(quest_id qidx, quest_state qstate, uint8_t qlog, int16_t qmsg)
+{
+	if (IsNoneOf(qlog, 0, 1))
+		return false;
+
+	if (qmsg < 0 || static_cast<size_t>(qmsg) >= SpeechCount)
+		return false;
+
+	switch (qstate) {
+	case QUEST_NOTAVAIL:
+	case QUEST_INIT:
+	case QUEST_ACTIVE:
+	case QUEST_DONE:
+		return true;
+
+	case QUEST_HIVE_TEASE1:
+	case QUEST_HIVE_TEASE2:
+	case QUEST_HIVE_ACTIVE:
+		return qidx == Q_JERSEY;
+
+	case QUEST_HIVE_DONE:
+		return IsAnyOf(qidx, Q_FARMER, Q_JERSEY);
+
+	default:
+		return false;
+	}
+}
+
+} // namespace devilution
diff --git a/Source/quests/validation.hpp b/Source/quests/validation.hpp
new file mode 100644
index 000000000..205458add
--- /dev/null
+++ b/Source/quests/validation.hpp
@@ -0,0 +1,17 @@
+/**
+ * @file quests/validation.hpp
+ *
+ * Interface of functions for validation of quest data.
+ */
+#pragma once
+
+#include <cstdint>
+
+#include "objdat.h"
+#include "quests.h"
+
+namespace devilution {
+
+bool IsQuestDeltaValid(quest_id qidx, quest_state qstate, uint8_t qlog, int16_t qmsg);
+
+} // namespace devilution
diff --git a/Source/textdat.cpp b/Source/textdat.cpp
index c5d2fbefd..4275bf854 100644
--- a/Source/textdat.cpp
+++ b/Source/textdat.cpp
@@ -916,4 +916,7 @@ const Speech Speeches[] = {
 	    1, 5, SfxID::Adria48 },
 */
 };
+
+const size_t SpeechCount = sizeof(Speeches) / sizeof(Speech);
+
 } // namespace devilution
diff --git a/Source/textdat.h b/Source/textdat.h
index c188b61df..1a8264cf2 100644
--- a/Source/textdat.h
+++ b/Source/textdat.h
@@ -5,6 +5,7 @@
  */
 #pragma once
 
+#include <cstddef>
 #include <cstdint>
 
 #include "sound_effect_enums.h"
@@ -430,6 +431,7 @@ struct Speech {
 	SfxID sfxnr;
 };
 
+extern const size_t SpeechCount;
 extern const Speech Speeches[];
 
 } // namespace devilution