diff --git a/Quake/common.c b/Quake/common.c
index 68f0174d..473a492d 100644
--- a/Quake/common.c
+++ b/Quake/common.c
@@ -1289,7 +1289,11 @@ static void COM_CheckRegistered (void)
 		Cvar_SetROM ("registered", "0");
 		Con_Printf ("Playing shareware version.\n");
 		if (com_modified)
-			Sys_Error ("You must have the registered version to use modified games");
+			Sys_Error ("You must have the registered version to use modified games.\n\n"
+				   "Basedir is: %s\n\n"
+				   "Check that this has an " GAMENAME " subdirectory containing pak0.pak and pak1.pak, "
+				   "or use the -basedir command-line option to specify another directory.",
+				   com_basedir);
 		return;
 	}
 
diff --git a/Quake/wad.c b/Quake/wad.c
index bd9f4fff..aae5f38f 100644
--- a/Quake/wad.c
+++ b/Quake/wad.c
@@ -79,7 +79,11 @@ void W_LoadWadFile (void) //johnfitz -- filename is now hard-coded for honesty
 		free (wad_base);
 	wad_base = COM_LoadMallocFile (filename, NULL);
 	if (!wad_base)
-		Sys_Error ("W_LoadWadFile: couldn't load %s", filename);
+		Sys_Error ("W_LoadWadFile: couldn't load %s\n\n"
+			   "Basedir is: %s\n\n"
+			   "Check that this has an " GAMENAME " subdirectory containing pak0.pak and pak1.pak, "
+			   "or use the -basedir command-line option to specify another directory.",
+			   filename, com_basedir);
 
 	header = (wadinfo_t *)wad_base;