diff --git a/engine/client/cl_main.c b/engine/client/cl_main.c
index 9a0f92dc..95e320e0 100644
--- a/engine/client/cl_main.c
+++ b/engine/client/cl_main.c
@@ -2830,19 +2830,26 @@ static void CL_Physinfo_f( void )
 static qboolean CL_ShouldRescanFilesystem( void )
 {
 	resource_t *res;
+	qboolean retval = false;
 
 	for( res = cl.resourcesonhand.pNext; res && res != &cl.resourcesonhand; res = res->pNext )
 	{
 		if( res->type == t_generic )
 		{
 			const char *ext = COM_FileExtension( res->szFileName );
-			// TODO: query supported archives format from fs_stdio
-			// TODO: query if was already opened
-			if( !Q_stricmp( ext, "wad" ) || !Q_stricmp( ext, "pk3" ) || !Q_stricmp( ext, "pak" ))
-				return true;
+
+			if( !g_fsapi.IsArchiveExtensionSupported( ext, IAES_ONLY_REAL_ARCHIVES ))
+				continue;
+
+			if( FBitSet( res->ucExtraFlags, RES_EXTRA_ARCHIVE_CHECKED ))
+				continue;
+
+			SetBits( res->ucExtraFlags, RES_EXTRA_ARCHIVE_CHECKED );
+			retval = true;
 		}
 	}
-	return false;
+
+	return retval;
 }
 
 qboolean CL_PrecacheResources( void )
diff --git a/engine/custom.h b/engine/custom.h
index 04d84894..3c8a0818 100644
--- a/engine/custom.h
+++ b/engine/custom.h
@@ -53,6 +53,10 @@ typedef struct resourceinfo_s
 #define RES_ALWAYS		(1<<5)	// Download always even if available on client
 #define RES_CHECKFILE	(1<<7)	// Check file on client
 
+// this archive was already mounted after rescan
+// only makes sense for archives and on client
+#define RES_EXTRA_ARCHIVE_CHECKED BIT( 0 )
+
 typedef struct resource_s
 {
 	char			szFileName[64];	// File name to download/precache.
@@ -67,6 +71,7 @@ typedef struct resource_s
 						// if it's a custom resource.
 
 	unsigned char		rguc_reserved[32];	// For future expansion
+	unsigned short		ucExtraFlags; // fwgs extension, doesn't change the size of struct because of compiler padding
 	struct resource_s		*pNext;		// Next in chain.
 	struct resource_s		*pPrev;
 } resource_t;