diff --git a/src/acs/call-funcs.cpp b/src/acs/call-funcs.cpp
index d87f2756e..f7354723d 100644
--- a/src/acs/call-funcs.cpp
+++ b/src/acs/call-funcs.cpp
@@ -2082,13 +2082,18 @@ bool CallFunc_DialogueSetCustomSpeaker(ACSVM::Thread *thread, const ACSVM::Word
 
 	patchStr = map->getString(argV[1]);
 	patchName = patchStr->str;
-	patch = static_cast<patch_t *>( W_CachePatchName(patchName, PU_CACHE) );
 
 	colorStr = map->getString(argV[2]);
 	colorName = colorStr->str;
-	if (ACS_GetColorFromString(colorName, &colorID) == true)
+
+	if (patchName && patchName[0])
 	{
-		colormap = R_GetTranslationColormap(TC_DEFAULT, colorID, GTC_CACHE);
+		patch = static_cast<patch_t *>( W_CachePatchName(patchName, PU_CACHE) );
+
+		if (ACS_GetColorFromString(colorName, &colorID) == true)
+		{
+			colormap = R_GetTranslationColormap(TC_DEFAULT, colorID, GTC_CACHE);
+		}
 	}
 
 	voiceStr = map->getString(argV[3]);