diff --git a/dovecot-2.3.13-bigtvsec.patch b/dovecot-2.3.13-bigtvsec.patch
new file mode 100644
index 0000000..1c91c0b
--- /dev/null
+++ b/dovecot-2.3.13-bigtvsec.patch
@@ -0,0 +1,36 @@
+diff -up dovecot-2.3.13/src/lib/test-time-util.c.bigtvsec dovecot-2.3.13/src/lib/test-time-util.c
+--- dovecot-2.3.13/src/lib/test-time-util.c.bigtvsec	2021-01-06 11:27:06.793315308 +0100
++++ dovecot-2.3.13/src/lib/test-time-util.c	2021-01-06 11:27:06.815315088 +0100
+@@ -358,7 +358,7 @@ static void test_str_to_timeval(void)
+ {
+ 	struct {
+ 		const char *str;
+-		time_t tv_sec, tv_usec;
++		long int tv_sec, tv_usec;
+ 	} tests[] = {
+ 		{ "0", 0, 0 },
+ 		{ "0.0", 0, 0 },
+diff -up dovecot-2.3.13/src/lib/time-util.c.bigtvsec dovecot-2.3.13/src/lib/time-util.c
+--- dovecot-2.3.13/src/lib/time-util.c.bigtvsec	2021-01-06 11:10:49.791094852 +0100
++++ dovecot-2.3.13/src/lib/time-util.c	2021-01-06 11:10:08.255501319 +0100
+@@ -43,16 +43,16 @@ int timeval_cmp_margin(const struct time
+ 
+ 	if (tv1->tv_sec < tv2->tv_sec) {
+ 		sec_margin = ((int)usec_margin / 1000000) + 1;
+-		if ((tv2->tv_sec - tv1->tv_sec) > sec_margin)
++		if (((long long)tv2->tv_sec - tv1->tv_sec) > sec_margin)
+ 			return -1;
+-		usecs_diff = (tv2->tv_sec - tv1->tv_sec) * 1000000LL +
++		usecs_diff = ((long long)tv2->tv_sec - tv1->tv_sec) * 1000000LL +
+ 			(tv2->tv_usec - tv1->tv_usec);
+ 		ret = -1;
+ 	} else if (tv1->tv_sec > tv2->tv_sec) {
+ 		sec_margin = ((int)usec_margin / 1000000) + 1;
+-		if ((tv1->tv_sec - tv2->tv_sec) > sec_margin)
++		if (((long long)tv1->tv_sec - tv2->tv_sec) > sec_margin)
+ 			return 1;
+-		usecs_diff = (tv1->tv_sec - tv2->tv_sec) * 1000000LL +
++		usecs_diff = ((long long)tv1->tv_sec - tv2->tv_sec) * 1000000LL +
+ 			(tv1->tv_usec - tv2->tv_usec);
+ 		ret = 1;
+ 	} else if (tv1->tv_usec < tv2->tv_usec) {
diff --git a/dovecot.spec b/dovecot.spec
index 1e16213..20e110d 100644
--- a/dovecot.spec
+++ b/dovecot.spec
@@ -33,6 +33,7 @@ Patch8: dovecot-2.2.20-initbysystemd.patch
 Patch9: dovecot-2.2.22-systemd_w_protectsystem.patch
 Patch10: dovecot-2.3.0.1-libxcrypt.patch
 Patch15: dovecot-2.3.11-bigkey.patch
+Patch16: dovecot-2.3.13-bigtvsec.patch
 
 Source15: prestartscript
 
@@ -122,6 +123,7 @@ This package provides the development files for dovecot.
 #patch13 -p1 -b .ftbfs2
 #patch14 -p1 -b .gssapi
 %patch15 -p1 -b .bigkey
+%patch16 -p1 -b .bigtvsec
 
 #pushd dovecot-2*3-pigeonhole-%{pigeonholever}
 #popd