diff --git a/t/lib-pack.sh b/t/lib-pack.sh
index fecd5a0279..7e8685b44c 100644
--- a/t/lib-pack.sh
+++ b/t/lib-pack.sh
@@ -55,6 +55,28 @@ pack_obj () {
 			printf '\062\170\234\143\267\3\0\0\116\0\106'
 			return
 			;;
+		01d7713666f4de822776c7622c10f1b07de280dc)
+			printf '\165\1\327\161\66\146\364\336\202\47\166' &&
+			printf '\307\142\54\20\361\260\175\342\200\334\170' &&
+			printf '\234\143\142\142\142\267\003\0\0\151\0\114'
+			return
+			;;
+		esac
+		;;
+
+	# blob containing "\7\0"
+	01d7713666f4de822776c7622c10f1b07de280dc)
+		case "$2" in
+		'')
+			printf '\062\170\234\143\147\0\0\0\20\0\10'
+			return
+			;;
+		e68fe8129b546b101aee9510c5328e7f21ca1d18)
+			printf '\165\346\217\350\22\233\124\153\20\32\356' &&
+			printf '\225\20\305\62\216\177\41\312\35\30\170\234' &&
+			printf '\143\142\142\142\147\0\0\0\53\0\16'
+			return
+			;;
 		esac
 		;;
 	esac
diff --git a/t/t5309-pack-delta-cycles.sh b/t/t5309-pack-delta-cycles.sh
new file mode 100755
index 0000000000..1640bf7764
--- /dev/null
+++ b/t/t5309-pack-delta-cycles.sh
@@ -0,0 +1,59 @@
+#!/bin/sh
+
+test_description='test index-pack handling of delta cycles in packfiles'
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-pack.sh
+
+# Two similar-ish objects that we have computed deltas between.
+A=01d7713666f4de822776c7622c10f1b07de280dc
+B=e68fe8129b546b101aee9510c5328e7f21ca1d18
+
+# double-check our hand-constucted packs
+test_expect_success 'index-pack works with a single delta (A->B)' '
+	clear_packs &&
+	{
+		pack_header 2 &&
+		pack_obj $A $B &&
+		pack_obj $B
+	} >ab.pack &&
+	pack_trailer ab.pack &&
+	git index-pack --stdin <ab.pack &&
+	git cat-file -t $A &&
+	git cat-file -t $B
+'
+
+test_expect_success 'index-pack works with a single delta (B->A)' '
+	clear_packs &&
+	{
+		pack_header 2 &&
+		pack_obj $A &&
+		pack_obj $B $A
+	} >ba.pack &&
+	pack_trailer ba.pack &&
+	git index-pack --stdin <ba.pack &&
+	git cat-file -t $A &&
+	git cat-file -t $B
+'
+
+test_expect_success 'index-pack detects missing base objects' '
+	clear_packs &&
+	{
+		pack_header 1 &&
+		pack_obj $A $B
+	} >missing.pack &&
+	pack_trailer missing.pack &&
+	test_must_fail git index-pack --fix-thin --stdin <missing.pack
+'
+
+test_expect_success 'index-pack detects REF_DELTA cycles' '
+	clear_packs &&
+	{
+		pack_header 2 &&
+		pack_obj $A $B &&
+		pack_obj $B $A
+	} >cycle.pack &&
+	pack_trailer cycle.pack &&
+	test_must_fail git index-pack --fix-thin --stdin <cycle.pack
+'
+
+test_done