diff --git a/src/d_netcmd.c b/src/d_netcmd.c
index 6043141b3..7a0185c17 100644
--- a/src/d_netcmd.c
+++ b/src/d_netcmd.c
@@ -4453,7 +4453,7 @@ static void Command_Addfilelocal(void)
 
 	if (COM_Argc() != 2)
 	{
-		CONS_Printf(M_GetText("addfile <wadfile.wad>: load wad file\n"));
+		CONS_Printf(M_GetText("addfilelocal <wadfile.wad>: load wad file\n"));
 		return;
 	}
 	else
@@ -4464,8 +4464,10 @@ static void Command_Addfilelocal(void)
 		if (!isprint(fn[i]) || fn[i] == ';')
 			return;
 
-	// Add file on your client directly if it is trivial, or you aren't in a netgame.
-	P_AddWadFile(fn);
+	// Add any wad file, ignoring checks for if it contains complex things like
+	// lua. Great for complex but client-side customizations, like different
+	// level cards or anything like that.
+	P_AddWadFileLocal(fn);
 }
 
 
diff --git a/src/d_netfil.c b/src/d_netfil.c
index a148a052d..49c12ce25 100644
--- a/src/d_netfil.c
+++ b/src/d_netfil.c
@@ -508,6 +508,9 @@ INT32 CL_CheckFiles(void)
 	if (modifiedgame)
 	{
 		CONS_Debug(DBG_NETPLAY, "game is modified; only doing basic checks\n");
+
+		boolean have_important = false;
+
 		for (i = 0, j = mainwads+1; i < fileneedednum || j < numwadfiles;)
 		{
 			if (j < numwadfiles && !wadfiles[j]->important)
@@ -517,10 +520,17 @@ INT32 CL_CheckFiles(void)
 				continue;
 			}
 
-			// If this test is true, we've reached the end of one file list
-			// and the other still has a file that's important
+			// If this test is true, we've reached the end of one file list.
 			if (i >= fileneedednum || j >= numwadfiles)
-				return 2;
+			{
+				// We are missing some of important files, or have too much
+				// important files.
+				if (have_important)
+					return 2;
+
+				// All checked files weren't important, don't care about them.
+				break;
+			}
 
 			// For the sake of speed, only bother with a md5 check
 			if (memcmp(wadfiles[j]->md5sum, fileneeded[i].md5sum, 16))
@@ -528,11 +538,14 @@ INT32 CL_CheckFiles(void)
 
 			// It's accounted for! let's keep going.
 			CONS_Debug(DBG_NETPLAY, "'%s' accounted for\n", fileneeded[i].filename);
+			have_important = true;
 			fileneeded[i].status = FS_OPEN;
 			++i;
 			++j;
 		}
-		return 1;
+
+		if (have_important)
+			return 1;
 	}
 
 	for (i = 0; i < fileneedednum; i++)
@@ -591,7 +604,7 @@ boolean CL_LoadServerFiles(void)
 			continue; // Already loaded
 		else if (fileneeded[i].status == FS_FOUND)
 		{
-			P_PartialAddWadFile(fileneeded[i].filename);
+			P_PartialAddWadFile(fileneeded[i].filename, false);
 			G_SetGameModified(true, false);
 			fileneeded[i].status = FS_OPEN;
 			return false;
diff --git a/src/g_game.c b/src/g_game.c
index 1749fae02..e778b19cc 100644
--- a/src/g_game.c
+++ b/src/g_game.c
@@ -7073,7 +7073,7 @@ static void G_LoadDemoExtraFiles(UINT8 **pp)
 			}
 			else
 			{
-				P_PartialAddWadFile(filename);
+				P_PartialAddWadFile(filename, false);
 			}
 		}
 	}
diff --git a/src/p_setup.c b/src/p_setup.c
index 95a89109d..f0bf34c9f 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -3453,7 +3453,18 @@ boolean P_AddWadFile(const char *wadfilename)
 {
 	UINT16 wadnum;
 
-	if ((wadnum = P_PartialAddWadFile(wadfilename)) == UINT16_MAX)
+	if ((wadnum = P_PartialAddWadFile(wadfilename, false)) == UINT16_MAX)
+		return false;
+
+	P_MultiSetupWadFiles(true);
+	return true;
+}
+
+boolean P_AddWadFileLocal(const char *wadfilename)
+{
+	UINT16 wadnum;
+
+	if ((wadnum = P_PartialAddWadFile(wadfilename, true)) == UINT16_MAX)
 		return false;
 
 	P_MultiSetupWadFiles(true);
@@ -3464,7 +3475,7 @@ boolean P_AddWadFile(const char *wadfilename)
 // Add a WAD file and do the per-WAD setup stages.
 // Call P_MultiSetupWadFiles as soon as possible after any number of these.
 //
-UINT16 P_PartialAddWadFile(const char *wadfilename)
+UINT16 P_PartialAddWadFile(const char *wadfilename, boolean local)
 {
 	size_t i, j, sreplaces = 0, mreplaces = 0, digmreplaces = 0;
 	UINT16 numlumps, wadnum;
@@ -3472,7 +3483,7 @@ UINT16 P_PartialAddWadFile(const char *wadfilename)
 	boolean mapsadded = false;
 	lumpinfo_t *lumpinfo;
 
-	if ((numlumps = W_InitFile(wadfilename)) == INT16_MAX)
+	if ((numlumps = W_InitFile(wadfilename, local)) == INT16_MAX)
 	{
 		refreshdirmenu |= REFRESHDIR_NOTLOADED;
 		CONS_Printf(M_GetText("Errors occurred while loading %s; not added.\n"), wadfilename);
diff --git a/src/p_setup.h b/src/p_setup.h
index 5ff53e13c..99269da00 100644
--- a/src/p_setup.h
+++ b/src/p_setup.h
@@ -61,6 +61,7 @@ void P_ScanThings(INT16 mapnum, INT16 wadnum, INT16 lumpnum);
 void P_LoadThingsOnly(void);
 boolean P_SetupLevel(boolean skipprecip);
 boolean P_AddWadFile(const char *wadfilename);
+boolean P_AddWadFileLocal(const char *wadfilename);
 #ifdef DELFILE
 boolean P_DelWadFile(void);
 #endif
@@ -68,7 +69,7 @@ boolean P_DelWadFile(void);
 // WARNING: The following functions should be grouped as follows:
 // any amount of PartialAdds followed by MultiSetups until returned true,
 // as soon as possible.
-UINT16 P_PartialAddWadFile(const char *wadfilename);
+UINT16 P_PartialAddWadFile(const char *wadfilename, boolean local);
 // Run a single stage of multisetup, or all of them if fullsetup set.
 //   fullsetup true: run everything
 //   otherwise
diff --git a/src/w_wad.c b/src/w_wad.c
index 040233487..31977bea8 100644
--- a/src/w_wad.c
+++ b/src/w_wad.c
@@ -690,7 +690,7 @@ static void W_ReadFileShaders(wadfile_t *wadfile)
 //
 // Can now load dehacked files (.soc)
 //
-UINT16 W_InitFile(const char *filename)
+UINT16 W_InitFile(const char *filename, boolean local)
 {
 	FILE *handle;
 	lumpinfo_t *lumpinfo = NULL;
@@ -729,7 +729,7 @@ UINT16 W_InitFile(const char *filename)
 	if ((handle = W_OpenWadFile(&filename, true)) == NULL)
 		return INT16_MAX;
 
-	important = !W_VerifyNMUSlumps(filename);
+	important = !local && !W_VerifyNMUSlumps(filename);
 
 #ifndef NOMD5
 	//
@@ -898,7 +898,7 @@ INT32 W_InitMultipleFiles(char **filenames, boolean addons)
 			G_SetGameModified(true, false);
 
 		//CONS_Debug(DBG_SETUP, "Loading %s\n", *filenames);
-		rc = W_InitFile(*filenames);
+		rc = W_InitFile(*filenames, false);
 		if (rc == INT16_MAX)
 			CONS_Printf(M_GetText("Errors occurred while loading %s; not added.\n"), *filenames);
 		overallrc &= (rc != INT16_MAX) ? 1 : 0;
diff --git a/src/w_wad.h b/src/w_wad.h
index 4a9be3c78..1c6e86c49 100644
--- a/src/w_wad.h
+++ b/src/w_wad.h
@@ -129,7 +129,10 @@ void W_Shutdown(void);
 // Opens a WAD file. Returns the FILE * handle for the file, or NULL if not found or could not be opened
 FILE *W_OpenWadFile(const char **filename, boolean useerrors);
 // Load and add a wadfile to the active wad files, returns numbers of lumps, INT16_MAX on error
-UINT16 W_InitFile(const char *filename);
+//
+// if local is true, it wouldn't check if file adds complex things, therefore
+// allowing to still join server without the "you have wrong addons loaded" error
+UINT16 W_InitFile(const char *filename, boolean local);
 #ifdef DELFILE
 void W_UnloadWadFile(UINT16 num);
 #endif