diff --git a/builtin/commit.c b/builtin/commit.c
index b2a6c7f100d82c4160c4bea6b4663af5459194cc..be370f64a995804ec6b62e03f7c6940044e08e24 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1730,7 +1730,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 				allow_fast_forward = 0;
 		}
 		if (allow_fast_forward)
-			parents = reduce_heads(parents);
+			reduce_heads_replace(&parents);
 	} else {
 		if (!reflog_msg)
 			reflog_msg = (whence == FROM_CHERRY_PICK)
diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c
index e99b5ddbf9a51be17bc0d976c942c29afe6563cd..27a2361e91dcd94cba4556b04b028286835f8823 100644
--- a/builtin/fmt-merge-msg.c
+++ b/builtin/fmt-merge-msg.c
@@ -571,7 +571,7 @@ static void find_merge_parents(struct merge_parents *result,
 	head_commit = lookup_commit(head);
 	if (head_commit)
 		commit_list_insert(head_commit, &parents);
-	parents = reduce_heads(parents);
+	reduce_heads_replace(&parents);
 
 	while (parents) {
 		struct commit *cmit = pop_commit(&parents);
diff --git a/builtin/merge-base.c b/builtin/merge-base.c
index 6dbd167d3b0874cd966b4590951a12d01f8f6aeb..24f6c7193546b91a8644a4417bfc6d6d94da6a62 100644
--- a/builtin/merge-base.c
+++ b/builtin/merge-base.c
@@ -9,20 +9,20 @@
 
 static int show_merge_base(struct commit **rev, int rev_nr, int show_all)
 {
-	struct commit_list *result;
+	struct commit_list *result, *r;
 
 	result = get_merge_bases_many_dirty(rev[0], rev_nr - 1, rev + 1);
 
 	if (!result)
 		return 1;
 
-	while (result) {
-		printf("%s\n", oid_to_hex(&result->item->object.oid));
+	for (r = result; r; r = r->next) {
+		printf("%s\n", oid_to_hex(&r->item->object.oid));
 		if (!show_all)
-			return 0;
-		result = result->next;
+			break;
 	}
 
+	free_commit_list(result);
 	return 0;
 }
 
@@ -51,45 +51,47 @@ static struct commit *get_commit_reference(const char *arg)
 
 static int handle_independent(int count, const char **args)
 {
-	struct commit_list *revs = NULL;
-	struct commit_list *result;
+	struct commit_list *revs = NULL, *rev;
 	int i;
 
 	for (i = count - 1; i >= 0; i--)
 		commit_list_insert(get_commit_reference(args[i]), &revs);
 
-	result = reduce_heads(revs);
-	if (!result)
+	reduce_heads_replace(&revs);
+
+	if (!revs)
 		return 1;
 
-	while (result) {
-		printf("%s\n", oid_to_hex(&result->item->object.oid));
-		result = result->next;
-	}
+	for (rev = revs; rev; rev = rev->next)
+		printf("%s\n", oid_to_hex(&rev->item->object.oid));
+
+	free_commit_list(revs);
 	return 0;
 }
 
 static int handle_octopus(int count, const char **args, int show_all)
 {
 	struct commit_list *revs = NULL;
-	struct commit_list *result;
+	struct commit_list *result, *rev;
 	int i;
 
 	for (i = count - 1; i >= 0; i--)
 		commit_list_insert(get_commit_reference(args[i]), &revs);
 
-	result = reduce_heads(get_octopus_merge_bases(revs));
+	result = get_octopus_merge_bases(revs);
+	free_commit_list(revs);
+	reduce_heads_replace(&result);
 
 	if (!result)
 		return 1;
 
-	while (result) {
-		printf("%s\n", oid_to_hex(&result->item->object.oid));
+	for (rev = result; rev; rev = rev->next) {
+		printf("%s\n", oid_to_hex(&rev->item->object.oid));
 		if (!show_all)
-			return 0;
-		result = result->next;
+			break;
 	}
 
+	free_commit_list(result);
 	return 0;
 }
 
diff --git a/builtin/merge.c b/builtin/merge.c
index ab5ffe85e8f5d7a359004f2bbb52a5778d0b91b4..fbbf2a9e5eb9be47d8574ca0bab175c5a6c0d15d 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -999,6 +999,7 @@ static struct commit_list *reduce_parents(struct commit *head_commit,
 
 	/* Find what parents to record by checking independent ones. */
 	parents = reduce_heads(remoteheads);
+	free_commit_list(remoteheads);
 
 	remoteheads = NULL;
 	remotes = &remoteheads;
diff --git a/builtin/pull.c b/builtin/pull.c
index 6f772e8a224c18238cf9a75436e8ea192765e7fe..4edab228ebe6c1d3df580689c7cf94eb989fe4bc 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -745,12 +745,15 @@ static int get_octopus_merge_base(struct object_id *merge_base,
 	if (!is_null_oid(fork_point))
 		commit_list_insert(lookup_commit_reference(fork_point), &revs);
 
-	result = reduce_heads(get_octopus_merge_bases(revs));
+	result = get_octopus_merge_bases(revs);
 	free_commit_list(revs);
+	reduce_heads_replace(&result);
+
 	if (!result)
 		return 1;
 
 	oidcpy(merge_base, &result->item->object.oid);
+	free_commit_list(result);
 	return 0;
 }
 
diff --git a/commit.c b/commit.c
index 1e0e633790bb834ad05ed9619e4afa0bac33ce19..cab8d4455bdbd6e4b87031613300be1112a19df5 100644
--- a/commit.c
+++ b/commit.c
@@ -1090,6 +1090,13 @@ struct commit_list *reduce_heads(struct commit_list *heads)
 	return result;
 }
 
+void reduce_heads_replace(struct commit_list **heads)
+{
+	struct commit_list *result = reduce_heads(*heads);
+	free_commit_list(*heads);
+	*heads = result;
+}
+
 static const char gpg_sig_header[] = "gpgsig";
 static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
 
diff --git a/commit.h b/commit.h
index 6d769590f285e534d20bfd8108e8e980253f8815..99a3fea68d3f63064351ccabeaf7f11cdf8e0d04 100644
--- a/commit.h
+++ b/commit.h
@@ -313,7 +313,23 @@ extern int interactive_add(int argc, const char **argv, const char *prefix, int
 extern int run_add_interactive(const char *revision, const char *patch_mode,
 			       const struct pathspec *pathspec);
 
-struct commit_list *reduce_heads(struct commit_list *heads);
+/*
+ * Takes a list of commits and returns a new list where those
+ * have been removed that can be reached from other commits in
+ * the list. It is useful for, e.g., reducing the commits
+ * randomly thrown at the git-merge command and removing
+ * redundant commits that the user shouldn't have given to it.
+ *
+ * This function destroys the STALE bit of the commit objects'
+ * flags.
+ */
+extern struct commit_list *reduce_heads(struct commit_list *heads);
+
+/*
+ * Like `reduce_heads()`, except it replaces the list. Use this
+ * instead of `foo = reduce_heads(foo);` to avoid memory leaks.
+ */
+extern void reduce_heads_replace(struct commit_list **heads);
 
 struct commit_extra_header {
 	struct commit_extra_header *next;