diff --git a/sha1-lookup.c b/sha1-lookup.c
index 2dd851598..5f069214d 100644
--- a/sha1-lookup.c
+++ b/sha1-lookup.c
@@ -84,8 +84,6 @@ int sha1_pos(const unsigned char *sha1, void *table, size_t nr,
 				die("BUG: assertion failed in binary search");
 			}
 		}
-		if (18 <= ofs)
-			die("cannot happen -- lo and hi are identical");
 	}
 
 	do {
diff --git a/t/t0064-sha1-array.sh b/t/t0064-sha1-array.sh
index 06549656c..50b31ffe7 100755
--- a/t/t0064-sha1-array.sh
+++ b/t/t0064-sha1-array.sh
@@ -71,4 +71,24 @@ test_expect_success 'lookup non-existing entry with duplicates' '
 	test "$n" -lt 0
 '
 
+test_expect_success 'lookup with almost duplicate values' '
+	{
+		echo "append 5555555555555555555555555555555555555555" &&
+		echo "append 555555555555555555555555555555555555555f" &&
+		echo20 lookup 55
+	} | test-sha1-array >actual &&
+	n=$(cat actual) &&
+	test "$n" -eq 0
+'
+
+test_expect_success 'lookup with single duplicate value' '
+	{
+		echo20 append 55 55 &&
+		echo20 lookup 55
+	} | test-sha1-array >actual &&
+	n=$(cat actual) &&
+	test "$n" -ge 0 &&
+	test "$n" -le 1
+'
+
 test_done