diff --git a/src/p_conversation.cpp b/src/p_conversation.cpp
index 2405755c5..02fef0a4f 100644
--- a/src/p_conversation.cpp
+++ b/src/p_conversation.cpp
@@ -377,7 +377,7 @@ static FStrifeDialogueNode *ReadRetailNode (const char *name, FileReader &lump,
 	if (name)
 	{
 		FStringf label("$TXT_DLG_%s_d%d_%s", name, int(pos), TokenFromString(speech.Dialogue).GetChars());
-		node->Dialogue = label;
+		node->Dialogue = GStrings.exists(label)? label : FString(speech.Dialogue);
 	}
 	else
 	{
@@ -401,6 +401,8 @@ static FStrifeDialogueNode *ReadRetailNode (const char *name, FileReader &lump,
 		label.ReplaceChars(' ', '_');
 		label.ReplaceChars('\'', '_');
 		node->SpeakerName.Format("$TXT_SPEAKER_%s", label.GetChars());
+		if (!GStrings.exists(node->SpeakerName)) node->SpeakerName = speech.Name;
+
 	}
 	else
 	{
@@ -471,7 +473,7 @@ static FStrifeDialogueNode *ReadTeaserNode (const char *name, FileReader &lump,
 	if (name)
 	{
 		FStringf label("$TXT_DLG_%s_d%d_%s", name, pos, TokenFromString(speech.Dialogue).GetChars());
-		node->Dialogue = label;
+		node->Dialogue = GStrings.exists(label)? label : FString(speech.Dialogue);
 	}
 	else
 	{
@@ -500,6 +502,7 @@ static FStrifeDialogueNode *ReadTeaserNode (const char *name, FileReader &lump,
 		label.ReplaceChars(' ', '_');
 		label.ReplaceChars('\'', '_');
 		node->SpeakerName.Format("$TXT_SPEAKER_%s", label.GetChars());
+		if (!GStrings.exists(node->SpeakerName)) node->SpeakerName = speech.Name;
 	}
 	else
 	{
@@ -591,6 +594,8 @@ static void ParseReplies (const char *name, int pos, FStrifeDialogueReply **repl
 		if (name)
 		{
 			FStringf label("$TXT_RPLY%d_%s_d%d_%s", j, name, pos, TokenFromString(rsp->Reply).GetChars());
+			reply->Reply = GStrings.exists(label)? label : FString(rsp->Reply);
+
 			reply->Reply = label;
 		}
 		else
@@ -615,7 +620,7 @@ static void ParseReplies (const char *name, int pos, FStrifeDialogueReply **repl
 			if (name)
 			{
 				FStringf label("$TXT_RYES%d_%s_d%d_%s", j, name, pos, TokenFromString(rsp->Yes).GetChars());
-				reply->QuickYes = label;
+				reply->QuickYes = GStrings.exists(label)? label : FString(rsp->Yes);
 			}
 			else
 			{
@@ -625,7 +630,7 @@ static void ParseReplies (const char *name, int pos, FStrifeDialogueReply **repl
 		if (reply->ItemCheck[0].Item != 0)
 		{
 			FStringf label("$TXT_RNO%d_%s_d%d_%s", j, name, pos, TokenFromString(rsp->No).GetChars());
-			reply->QuickNo = label;
+			reply->QuickNo = GStrings.exists(label)? label : FString(rsp->No);
 		}
 		else
 		{
diff --git a/src/stringtable.cpp b/src/stringtable.cpp
index c57e6e031..bc15b83f4 100644
--- a/src/stringtable.cpp
+++ b/src/stringtable.cpp
@@ -210,6 +210,32 @@ size_t FStringTable::ProcessEscapes (char *iptr)
 	return optr - sptr;
 }
 
+bool FStringTable::exists(const char *name)
+{
+	// Checks if the given key exists in any one of the default string tables that are valid for all languages.
+	// To replace IWAD content this condition must be true.
+	if (name == nullptr || *name == 0)
+	{
+		return false;
+	}
+	FName nm(name, true);
+	if (nm != NAME_None)
+	{
+		uint32_t defaultStrings[] = { MAKE_ID('*', '*', '*', 0), MAKE_ID('*', 0, 0, 0), MAKE_ID('*', '*', 0, 0) };
+
+		for (auto mapid : defaultStrings)
+		{
+			auto map = allStrings.CheckKey(mapid);
+			if (map)
+			{
+				auto item = map->CheckKey(nm);
+				if (item) return true;
+			}
+		}
+	}
+	return false;
+}
+
 // Finds a string by name and returns its value
 const char *FStringTable::operator[] (const char *name) const
 {
diff --git a/src/stringtable.h b/src/stringtable.h
index 1c479ba5a..11416367c 100644
--- a/src/stringtable.h
+++ b/src/stringtable.h
@@ -71,6 +71,7 @@ public:
 
 	const char *operator() (const char *name) const;	// Never returns NULL
 	const char *operator[] (const char *name) const;	// Can return NULL
+	bool exists(const char *name);
 
 private: