diff --git a/external/bsd/file/dist/magic/magdir/diff b/external/bsd/file/dist/magic/magdir/diff
index 291bae67f55e..218a0bddf86d 100644
--- a/external/bsd/file/dist/magic/magdir/diff
+++ b/external/bsd/file/dist/magic/magdir/diff
@@ -12,3 +12,8 @@
 
 0	search/1	Index:		RCS/CVS diff output text
 !:mime	text/x-diff
+#
+#------------------------------------------------------------------------------
+# bsdiff:  file(1) magic for bsdiff(1) output
+#
+0	string		BSDIFF40	bsdiff(1) patch file