diff --git a/builtin-reflog.c b/builtin-reflog.c
index d3f2f50d2bc7b4ef0f0e4801c70c5a15ff869f1f..1da7da0916af92eed0a3168036175376f0ac0c0a 100644
--- a/builtin-reflog.c
+++ b/builtin-reflog.c
@@ -4,16 +4,34 @@
 #include "refs.h"
 #include "dir.h"
 #include "tree-walk.h"
+#include "diff.h"
+#include "revision.h"
+#include "reachable.h"
+
+/*
+ * reflog expire
+ */
+
+static const char reflog_expire_usage[] =
+"git-reflog expire [--verbose] [--dry-run] [--fix-stale] [--expire=<time>] [--expire-unreachable=<time>] [--all] <refs>...";
 
 static unsigned long default_reflog_expire;
 static unsigned long default_reflog_expire_unreachable;
 
+struct cmd_reflog_expire_cb {
+	struct rev_info revs;
+	int dry_run;
+	int stalefix;
+	int verbose;
+	unsigned long expire_total;
+	unsigned long expire_unreachable;
+};
+
 struct expire_reflog_cb {
 	FILE *newlog;
 	const char *ref;
 	struct commit *ref_commit;
-	unsigned long expire_total;
-	unsigned long expire_unreachable;
+	struct cmd_reflog_expire_cb *cmd;
 };
 
 static int tree_is_complete(const unsigned char *sha1)
@@ -43,6 +61,83 @@ static int tree_is_complete(const unsigned char *sha1)
 	return 1;
 }
 
+#define INCOMPLETE	(1u<<10)
+#define STUDYING	(1u<<11)
+
+static int commit_is_complete(struct commit *commit)
+{
+	struct object_array study;
+	struct object_array found;
+	int is_incomplete = 0;
+	int i;
+
+	/* early return */
+	if (commit->object.flags & SEEN)
+		return 1;
+	if (commit->object.flags & INCOMPLETE)
+		return 0;
+	/*
+	 * Find all commits that are reachable and are not marked as
+	 * SEEN.  Then make sure the trees and blobs contained are
+	 * complete.  After that, mark these commits also as SEEN.
+	 * If some of the objects that are needed to complete this
+	 * commit are missing, mark this commit as INCOMPLETE.
+	 */
+	memset(&study, 0, sizeof(study));
+	memset(&found, 0, sizeof(found));
+	add_object_array(&commit->object, NULL, &study);
+	add_object_array(&commit->object, NULL, &found);
+	commit->object.flags |= STUDYING;
+	while (study.nr) {
+		struct commit *c;
+		struct commit_list *parent;
+
+		c = (struct commit *)study.objects[--study.nr].item;
+		if (!c->object.parsed && !parse_object(c->object.sha1))
+			c->object.flags |= INCOMPLETE;
+
+		if (c->object.flags & INCOMPLETE) {
+			is_incomplete = 1;
+			break;
+		}
+		else if (c->object.flags & SEEN)
+			continue;
+		for (parent = c->parents; parent; parent = parent->next) {
+			struct commit *p = parent->item;
+			if (p->object.flags & STUDYING)
+				continue;
+			p->object.flags |= STUDYING;
+			add_object_array(&p->object, NULL, &study);
+			add_object_array(&p->object, NULL, &found);
+		}
+	}
+	if (!is_incomplete) {
+		/* make sure all commits in found have all the
+		 * necessary objects.
+		 */
+		for (i = 0; !is_incomplete && i < found.nr; i++) {
+			struct commit *c =
+				(struct commit *)found.objects[i].item;
+			if (!tree_is_complete(c->tree->object.sha1))
+				is_incomplete = 1;
+		}
+		if (!is_incomplete) {
+			/* mark all found commits as complete, iow SEEN */
+			for (i = 0; i < found.nr; i++)
+				found.objects[i].item->flags |= SEEN;
+		}
+	}
+	/* clear flags from the objects we traversed */
+	for (i = 0; i < found.nr; i++)
+		found.objects[i].item->flags &= ~STUDYING;
+	if (is_incomplete)
+		commit->object.flags |= INCOMPLETE;
+	/* free object arrays */
+	free(study.objects);
+	free(found.objects);
+	return !is_incomplete;
+}
+
 static int keep_entry(struct commit **it, unsigned char *sha1)
 {
 	struct commit *commit;
@@ -54,9 +149,15 @@ static int keep_entry(struct commit **it, unsigned char *sha1)
 	if (!commit)
 		return 0;
 
-	/* Make sure everything in this commit exists. */
-	parse_object(commit->object.sha1);
-	if (!tree_is_complete(commit->tree->object.sha1))
+	/*
+	 * Make sure everything in this commit exists.
+	 *
+	 * We have walked all the objects reachable from the refs
+	 * and cache earlier.  The commits reachable by this commit
+	 * must meet SEEN commits -- and then we should mark them as
+	 * SEEN as well.
+	 */
+	if (!commit_is_complete(commit))
 		return 0;
 	*it = commit;
 	return 1;
@@ -76,13 +177,14 @@ static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 	timestamp = strtoul(cp, &ep, 10);
 	if (*ep != ' ')
 		goto prune;
-	if (timestamp < cb->expire_total)
+	if (timestamp < cb->cmd->expire_total)
 		goto prune;
 
-	if (!keep_entry(&old, osha1) || !keep_entry(&new, nsha1))
+	if (cb->cmd->stalefix &&
+	    (!keep_entry(&old, osha1) || !keep_entry(&new, nsha1)))
 		goto prune;
 
-	if ((timestamp < cb->expire_unreachable) &&
+	if ((timestamp < cb->cmd->expire_unreachable) &&
 	    (!cb->ref_commit ||
 	     (old && !in_merge_bases(old, cb->ref_commit)) ||
 	     (new && !in_merge_bases(new, cb->ref_commit))))
@@ -91,19 +193,15 @@ static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 	if (cb->newlog)
 		fprintf(cb->newlog, "%s %s %s",
 			sha1_to_hex(osha1), sha1_to_hex(nsha1), data);
+	if (cb->cmd->verbose)
+		printf("keep %s", data);
 	return 0;
  prune:
-	if (!cb->newlog)
-		fprintf(stderr, "would prune %s", data);
+	if (!cb->newlog || cb->cmd->verbose)
+		printf("%sprune %s", cb->newlog ? "" : "would ", data);
 	return 0;
 }
 
-struct cmd_reflog_expire_cb {
-	int dry_run;
-	unsigned long expire_total;
-	unsigned long expire_unreachable;
-};
-
 static int expire_reflog(const char *ref, const unsigned char *sha1, int unused, void *cb_data)
 {
 	struct cmd_reflog_expire_cb *cmd = cb_data;
@@ -134,8 +232,7 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
 		fprintf(stderr,
 			"warning: ref '%s' does not point at a commit\n", ref);
 	cb.ref = ref;
-	cb.expire_total = cmd->expire_total;
-	cb.expire_unreachable = cmd->expire_unreachable;
+	cb.cmd = cmd;
 	for_each_reflog_ent(ref, expire_reflog_ent, &cb);
  finish:
 	if (cb.newlog) {
@@ -164,9 +261,6 @@ static int reflog_expire_config(const char *var, const char *value)
 	return 0;
 }
 
-static const char reflog_expire_usage[] =
-"git-reflog expire [--dry-run] [--expire=<time>] [--expire-unreachable=<time>] [--all] <refs>...";
-
 static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 {
 	struct cmd_reflog_expire_cb cb;
@@ -186,6 +280,12 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 	cb.expire_total = default_reflog_expire;
 	cb.expire_unreachable = default_reflog_expire_unreachable;
 
+	/*
+	 * We can trust the commits and objects reachable from refs
+	 * even in older repository.  We cannot trust what's reachable
+	 * from reflog if the repository was pruned with older git.
+	 */
+
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
 		if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
@@ -194,8 +294,12 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 			cb.expire_total = approxidate(arg + 9);
 		else if (!strncmp(arg, "--expire-unreachable=", 21))
 			cb.expire_unreachable = approxidate(arg + 21);
+		else if (!strcmp(arg, "--stale-fix"))
+			cb.stalefix = 1;
 		else if (!strcmp(arg, "--all"))
 			do_all = 1;
+		else if (!strcmp(arg, "--verbose"))
+			cb.verbose = 1;
 		else if (!strcmp(arg, "--")) {
 			i++;
 			break;
@@ -205,6 +309,15 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 		else
 			break;
 	}
+	if (cb.stalefix) {
+		init_revisions(&cb.revs, prefix);
+		if (cb.verbose)
+			printf("Marking reachable objects...");
+		mark_reachable_objects(&cb.revs, 0);
+		if (cb.verbose)
+			putchar('\n');
+	}
+
 	if (do_all)
 		status |= for_each_ref(expire_reflog, &cb);
 	while (i < argc) {
@@ -219,6 +332,10 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 	return status;
 }
 
+/*
+ * main "reflog"
+ */
+
 static const char reflog_usage[] =
 "git-reflog (expire | ...)";
 
diff --git a/t/t1410-reflog.sh b/t/t1410-reflog.sh
new file mode 100755
index 0000000000000000000000000000000000000000..738d1513d49356d4e7a8eaec4b5df61a0e07881c
--- /dev/null
+++ b/t/t1410-reflog.sh
@@ -0,0 +1,176 @@
+#!/bin/sh
+#
+# Copyright (c) 2007 Junio C Hamano
+#
+
+test_description='Test prune and reflog expiration'
+. ./test-lib.sh
+
+check_have () {
+	gaah= &&
+	for N in "$@"
+	do
+		eval "o=\$$N" && git cat-file -t $o || {
+			echo Gaah $N
+			gaah=$N
+			break
+		}
+	done &&
+	test -z "$gaah"
+}
+
+check_fsck () {
+	output=$(git fsck-objects --full)
+	case "$1" in
+	'')
+		test -z "$output" ;;
+	*)
+		echo "$output" | grep "$1" ;;
+	esac
+}
+
+corrupt () {
+	aa=${1%??????????????????????????????????????} zz=${1#??}
+	mv .git/objects/$aa/$zz .git/$aa$zz
+}
+
+recover () {
+	aa=${1%??????????????????????????????????????} zz=${1#??}
+	mkdir -p .git/objects/$aa
+	mv .git/$aa$zz .git/objects/$aa/$zz
+}
+
+check_dont_have () {
+	gaah= &&
+	for N in "$@"
+	do
+		eval "o=\$$N"
+		git cat-file -t $o && {
+			echo Gaah $N
+			gaah=$N
+			break
+		}
+	done
+	test -z "$gaah"
+}
+
+test_expect_success setup '
+	mkdir -p A/B &&
+	echo rat >C &&
+	echo ox >A/D &&
+	echo tiger >A/B/E &&
+	git add . &&
+
+	test_tick && git commit -m rabbit &&
+	H=`git rev-parse --verify HEAD` &&
+	A=`git rev-parse --verify HEAD:A` &&
+	B=`git rev-parse --verify HEAD:A/B` &&
+	C=`git rev-parse --verify HEAD:C` &&
+	D=`git rev-parse --verify HEAD:A/D` &&
+	E=`git rev-parse --verify HEAD:A/B/E` &&
+	check_fsck &&
+
+	chmod +x C &&
+	git add C &&
+	test_tick && git commit -m dragon &&
+	L=`git rev-parse --verify HEAD` &&
+	check_fsck &&
+
+	rm -f C A/B/E &&
+	echo snake >F &&
+	echo horse >A/G &&
+	git add F A/G &&
+	test_tick && git commit -a -m sheep &&
+	F=`git rev-parse --verify HEAD:F` &&
+	G=`git rev-parse --verify HEAD:A/G` &&
+	I=`git rev-parse --verify HEAD:A` &&
+	J=`git rev-parse --verify HEAD` &&
+	check_fsck &&
+
+	rm -f A/G &&
+	test_tick && git commit -a -m monkey &&
+	K=`git rev-parse --verify HEAD` &&
+	check_fsck &&
+
+	check_have A B C D E F G H I J K L &&
+
+	git prune &&
+
+	check_have A B C D E F G H I J K L &&
+
+	check_fsck &&
+
+	loglen=$(wc -l <.git/logs/refs/heads/master) &&
+	test $loglen = 4
+'
+
+test_expect_success rewind '
+	test_tick && git reset --hard HEAD~2 &&
+	test -f C &&
+	test -f A/B/E &&
+	! test -f F &&
+	! test -f A/G &&
+
+	check_have A B C D E F G H I J K L &&
+
+	git prune &&
+
+	check_have A B C D E F G H I J K L &&
+
+	loglen=$(wc -l <.git/logs/refs/heads/master) &&
+	test $loglen = 5
+'
+
+test_expect_success 'corrupt and check' '
+
+	corrupt $F &&
+	check_fsck "missing blob $F"
+
+'
+
+test_expect_success 'reflog expire --dry-run should not touch reflog' '
+
+	git reflog expire --dry-run \
+		--expire=$(($test_tick - 10000)) \
+		--expire-unreachable=$(($test_tick - 10000)) \
+		--stale-fix \
+		--all &&
+
+	loglen=$(wc -l <.git/logs/refs/heads/master) &&
+	test $loglen = 5 &&
+
+	check_fsck "missing blob $F"
+'
+
+test_expect_success 'reflog expire' '
+
+	git reflog expire --verbose \
+		--expire=$(($test_tick - 10000)) \
+		--expire-unreachable=$(($test_tick - 10000)) \
+		--stale-fix \
+		--all &&
+
+	loglen=$(wc -l <.git/logs/refs/heads/master) &&
+	test $loglen = 2 &&
+
+	check_fsck "dangling commit $K"
+'
+
+test_expect_success 'prune and fsck' '
+
+	git prune &&
+	check_fsck &&
+
+	check_have A B C D E H L &&
+	check_dont_have F G I J K
+
+'
+
+test_expect_success 'recover and check' '
+
+	recover $F &&
+	check_fsck "dangling blob $F"
+
+'
+
+test_done