diff --git a/usr.sbin/makefs/makefs.8 b/usr.sbin/makefs/makefs.8
--- a/usr.sbin/makefs/makefs.8
+++ b/usr.sbin/makefs/makefs.8
@@ -33,7 +33,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd January 19, 2024
+.Dd April 7, 2025
 
 .Dt MAKEFS 8
 .Os
@@ -594,6 +594,24 @@
 .It setuid
 .El
 .El
+.Sh ENVIRONMENT
+.Bl -tag
+.It Ev SOURCE_DATE_EPOCH
+The
+.Ev SOURCE_DATE_EPOCH
+environment variable can be used to specify a timestamp
+in the same way as the
+.Fl T
+flag. When both
+.Ev SOURCE_DATE_EPOCH
+and
+.Fl T
+are present, the timestamp specified by the
+.Ev SOURCE_DATE_EPOCH
+variable overrides the timestamp specified by the
+.Fl T
+flag.
+.Pp
 .Sh SEE ALSO
 .Xr mtree 5 ,
 .Xr rc.conf 5 ,
diff --git a/usr.sbin/makefs/makefs.c b/usr.sbin/makefs/makefs.c
--- a/usr.sbin/makefs/makefs.c
+++ b/usr.sbin/makefs/makefs.c
@@ -98,6 +98,7 @@
 	fsinfo_t	 fsoptions;
 	fsnode		*root;
 	int		 ch, i, len;
+	const char	*env;
 	const char	*subtree;
 	const char	*specfile;
 
@@ -126,6 +127,9 @@
 	if (ch == -1)
 		err(1, "Unable to get system time");
 
+	env = getenv("SOURCE_DATE_EPOCH");
+	if (env != NULL && get_tstamp(env, &stampst) == -1)
+		errx(1, "Cannot get timestamp from SOURCE_DATE_EPOCH");
 
 	while ((ch = getopt(argc, argv, "B:b:Dd:f:F:M:m:N:O:o:pR:s:S:t:T:xZ")) != -1) {
 		switch (ch) {
diff --git a/usr.sbin/makefs/tests/makefs_ffs_tests.sh b/usr.sbin/makefs/tests/makefs_ffs_tests.sh
--- a/usr.sbin/makefs/tests/makefs_ffs_tests.sh
+++ b/usr.sbin/makefs/tests/makefs_ffs_tests.sh
@@ -288,6 +288,53 @@
 	common_cleanup
 }
 
+atf_test_case source_date_epoch cleanup
+source_date_epoch_body()
+{
+	timestamp=1742574909
+	create_test_dirs
+
+	mkdir -p $TEST_INPUTS_DIR/dir1
+	export SOURCE_DATE_EPOCH=$timestamp
+	atf_check -e empty -o not-empty -s exit:0 \
+	    $MAKEFS -M 1m $TEST_IMAGE $TEST_INPUTS_DIR
+
+	mount_image
+	eval $(stat -s  $TEST_MOUNT_DIR/dir1)
+	atf_check_equal $st_atime $timestamp
+	atf_check_equal $st_mtime $timestamp
+	atf_check_equal $st_ctime $timestamp
+}
+
+source_date_epoch_cleanup()
+{
+	common_cleanup
+}
+
+atf_test_case T_flag_source_date_epoch cleanup
+T_flag_source_date_epoch_body()
+{
+	timestamp_env=1742574909
+	timestamp_T=1742574910
+	create_test_dirs
+
+	mkdir -p $TEST_INPUTS_DIR/dir1
+	export SOURCE_DATE_EPOCH=$timestamp_env
+	atf_check -e empty -o not-empty -s exit:0 \
+	    $MAKEFS -T $timestamp_T -M 1m $TEST_IMAGE $TEST_INPUTS_DIR
+
+	mount_image
+	eval $(stat -s  $TEST_MOUNT_DIR/dir1)
+	atf_check_equal $st_atime $timestamp_T
+	atf_check_equal $st_mtime $timestamp_T
+	atf_check_equal $st_ctime $timestamp_T
+}
+
+T_flag_source_date_epoch_cleanup()
+{
+	common_cleanup
+}
+
 atf_init_test_cases()
 {
 
@@ -299,9 +346,11 @@
 	atf_add_test_case from_mtree_spec_file
 	atf_add_test_case from_multiple_dirs
 	atf_add_test_case from_single_dir
+	atf_add_test_case source_date_epoch
 
 	atf_add_test_case o_flag_version_1
 	atf_add_test_case o_flag_version_2
 	atf_add_test_case T_flag_dir
 	atf_add_test_case T_flag_mtree
+	atf_add_test_case T_flag_source_date_epoch
 }