diff --git a/include/osmocom/core/tdef.h b/include/osmocom/core/tdef.h
index 54819d9..627ba3f 100644
--- a/include/osmocom/core/tdef.h
+++ b/include/osmocom/core/tdef.h
@@ -40,6 +40,7 @@
 	OSMO_TDEF_MS,		/*!< milliseconds */
 	OSMO_TDEF_M,		/*!< minutes */
 	OSMO_TDEF_CUSTOM,	/*!< unspecified unit, explained in osmo_tdef.desc. */
+	OSMO_TDEF_US,		/*!< microseconds */
 };
 
 extern const struct value_string osmo_tdef_unit_names[];
diff --git a/src/tdef.c b/src/tdef.c
index 71a3315..897a92f 100644
--- a/src/tdef.c
+++ b/src/tdef.c
@@ -93,6 +93,17 @@
 		return 1;
 
 	switch (b) {
+	case OSMO_TDEF_US:
+		switch (a) {
+		case OSMO_TDEF_MS:
+			return 1000;
+		case OSMO_TDEF_S:
+			return 1000*1000;
+		case OSMO_TDEF_M:
+			return 60*1000*1000;
+		default:
+			return 0;
+		}
 	case OSMO_TDEF_MS:
 		switch (a) {
 		case OSMO_TDEF_S:
@@ -351,6 +362,7 @@
 	{ OSMO_TDEF_MS, "ms" },
 	{ OSMO_TDEF_M, "m" },
 	{ OSMO_TDEF_CUSTOM, "custom-unit" },
+	{ OSMO_TDEF_US, "us" },
 	{}
 };
 
diff --git a/tests/tdef/tdef_test.c b/tests/tdef/tdef_test.c
index 9c0808e..d874231 100644
--- a/tests/tdef/tdef_test.c
+++ b/tests/tdef/tdef_test.c
@@ -54,6 +54,7 @@
 	{ .T=1006, .default_val=0, .unit=OSMO_TDEF_S, .desc="zero s" },
 	{ .T=1007, .default_val=0, .unit=OSMO_TDEF_M, .desc="zero m" },
 	{ .T=1008, .default_val=0, .unit=OSMO_TDEF_CUSTOM, .desc="zero" },
+	{ .T=1009, .default_val=0, .unit=OSMO_TDEF_US, .desc="zero us" },
 
 	{ .T=0, .default_val=1, .unit=OSMO_TDEF_CUSTOM, .desc="zero" },
 
@@ -111,7 +112,7 @@
 	for (i = 0; i < ARRAY_SIZE(tdefs)-1; i++) {
 		unsigned int T = tdefs[i].T;
 		print_tdef_info(T);
-		for (as_unit = OSMO_TDEF_S; as_unit <= OSMO_TDEF_CUSTOM; as_unit++) {
+		for (as_unit = OSMO_TDEF_S; as_unit <= OSMO_TDEF_US; as_unit++) {
 			print_tdef_get_short(tdefs, T, as_unit);
 		}
 	}
@@ -122,7 +123,7 @@
 	for (i = 0; i < ARRAY_SIZE(tdefs_range)-1; i++) {
 		unsigned int T = tdefs_range[i].T;
 		print_tdef_info(T);
-		for (as_unit = OSMO_TDEF_S; as_unit <= OSMO_TDEF_CUSTOM; as_unit++) {
+		for (as_unit = OSMO_TDEF_S; as_unit <= OSMO_TDEF_US; as_unit++) {
 			print_tdef_get_short(tdefs_range, T, as_unit);
 		}
 	}
@@ -136,6 +137,7 @@
 	print_tdef_get(tdefs, 5, OSMO_TDEF_MS);
 	print_tdef_get(tdefs, 5, OSMO_TDEF_M);
 	print_tdef_get(tdefs, 5, OSMO_TDEF_CUSTOM);
+	print_tdef_get(tdefs, 5, OSMO_TDEF_US);
 }
 
 static void test_tdef_set_and_get()
@@ -152,6 +154,7 @@
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_S);
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_M);
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_CUSTOM);
+	print_tdef_get_short(tdefs, 7, OSMO_TDEF_US);
 
 	printf("setting 7 = 420\n");
 	OSMO_ASSERT(osmo_tdef_set(tdefs, 7, 420, OSMO_TDEF_S) == 0);
@@ -160,6 +163,7 @@
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_S);
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_M);
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_CUSTOM);
+	print_tdef_get_short(tdefs, 7, OSMO_TDEF_US);
 
 	printf("setting 7 = 10 (ERANGE)\n");
 	OSMO_ASSERT(!osmo_tdef_val_in_range(t, 10));
@@ -169,6 +173,7 @@
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_S);
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_M);
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_CUSTOM);
+	print_tdef_get_short(tdefs, 7, OSMO_TDEF_US);
 
 	printf("setting 7 = 900 (ERANGE)\n");
 	OSMO_ASSERT(!osmo_tdef_val_in_range(t, 900));
@@ -178,6 +183,7 @@
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_S);
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_M);
 	print_tdef_get_short(tdefs, 7, OSMO_TDEF_CUSTOM);
+	print_tdef_get_short(tdefs, 7, OSMO_TDEF_US);
 
 	printf("setting 23 = 50 (EEXIST)\n");
 	OSMO_ASSERT(osmo_tdef_set(tdefs, 23, 50, OSMO_TDEF_S) == -EEXIST);
diff --git a/tests/tdef/tdef_test.ok b/tests/tdef/tdef_test.ok
index 3c4a093..1770968 100644
--- a/tests/tdef/tdef_test.ok
+++ b/tests/tdef/tdef_test.ok
@@ -5,92 +5,116 @@
 osmo_tdef_get(1, ms)	= 100000
 osmo_tdef_get(1, m)	= 2
 osmo_tdef_get(1, custom-unit)	= 100
+osmo_tdef_get(1, us)	= 100000000
 T2=100ms
 osmo_tdef_get(2, s)	= 1
 osmo_tdef_get(2, ms)	= 100
 osmo_tdef_get(2, m)	= 1
 osmo_tdef_get(2, custom-unit)	= 100
+osmo_tdef_get(2, us)	= 100000
 T3=100m
 osmo_tdef_get(3, s)	= 6000
 osmo_tdef_get(3, ms)	= 6000000
 osmo_tdef_get(3, m)	= 100
 osmo_tdef_get(3, custom-unit)	= 100
+osmo_tdef_get(3, us)	= 6000000000
 T4=100custom-unit
 osmo_tdef_get(4, s)	= 100
 osmo_tdef_get(4, ms)	= 100
 osmo_tdef_get(4, m)	= 100
 osmo_tdef_get(4, custom-unit)	= 100
+osmo_tdef_get(4, us)	= 100
 T7=50s
 osmo_tdef_get(7, s)	= 50
 osmo_tdef_get(7, ms)	= 50000
 osmo_tdef_get(7, m)	= 1
 osmo_tdef_get(7, custom-unit)	= 50
+osmo_tdef_get(7, us)	= 50000000
 T8=300s
 osmo_tdef_get(8, s)	= 300
 osmo_tdef_get(8, ms)	= 300000
 osmo_tdef_get(8, m)	= 5
 osmo_tdef_get(8, custom-unit)	= 300
+osmo_tdef_get(8, us)	= 300000000
 T9=5m
 osmo_tdef_get(9, s)	= 300
 osmo_tdef_get(9, ms)	= 300000
 osmo_tdef_get(9, m)	= 5
 osmo_tdef_get(9, custom-unit)	= 5
+osmo_tdef_get(9, us)	= 300000000
 T10=20m
 osmo_tdef_get(10, s)	= 1200
 osmo_tdef_get(10, ms)	= 1200000
 osmo_tdef_get(10, m)	= 20
 osmo_tdef_get(10, custom-unit)	= 20
+osmo_tdef_get(10, us)	= 1200000000
 T1000=2000ms
 osmo_tdef_get(1000, s)	= 2
 osmo_tdef_get(1000, ms)	= 2000
 osmo_tdef_get(1000, m)	= 1
 osmo_tdef_get(1000, custom-unit)	= 2000
+osmo_tdef_get(1000, us)	= 2000000
 T1001=60000ms
 osmo_tdef_get(1001, s)	= 60
 osmo_tdef_get(1001, ms)	= 60000
 osmo_tdef_get(1001, m)	= 1
 osmo_tdef_get(1001, custom-unit)	= 60000
+osmo_tdef_get(1001, us)	= 60000000
 T1004=1ms
 osmo_tdef_get(1004, s)	= 1
 osmo_tdef_get(1004, ms)	= 1
 osmo_tdef_get(1004, m)	= 1
 osmo_tdef_get(1004, custom-unit)	= 1
+osmo_tdef_get(1004, us)	= 1000
 T1005=0ms
 osmo_tdef_get(1005, s)	= 0
 osmo_tdef_get(1005, ms)	= 0
 osmo_tdef_get(1005, m)	= 0
 osmo_tdef_get(1005, custom-unit)	= 0
+osmo_tdef_get(1005, us)	= 0
 T1006=0s
 osmo_tdef_get(1006, s)	= 0
 osmo_tdef_get(1006, ms)	= 0
 osmo_tdef_get(1006, m)	= 0
 osmo_tdef_get(1006, custom-unit)	= 0
+osmo_tdef_get(1006, us)	= 0
 T1007=0m
 osmo_tdef_get(1007, s)	= 0
 osmo_tdef_get(1007, ms)	= 0
 osmo_tdef_get(1007, m)	= 0
 osmo_tdef_get(1007, custom-unit)	= 0
+osmo_tdef_get(1007, us)	= 0
 T1008=0custom-unit
 osmo_tdef_get(1008, s)	= 0
 osmo_tdef_get(1008, ms)	= 0
 osmo_tdef_get(1008, m)	= 0
 osmo_tdef_get(1008, custom-unit)	= 0
+osmo_tdef_get(1008, us)	= 0
+T1009=0us
+osmo_tdef_get(1009, s)	= 0
+osmo_tdef_get(1009, ms)	= 0
+osmo_tdef_get(1009, m)	= 0
+osmo_tdef_get(1009, custom-unit)	= 0
+osmo_tdef_get(1009, us)	= 0
 T0=1custom-unit
 osmo_tdef_get(0, s)	= 1
 osmo_tdef_get(0, ms)	= 1
 osmo_tdef_get(0, m)	= 1
 osmo_tdef_get(0, custom-unit)	= 1
+osmo_tdef_get(0, us)	= 1
 T123=1s
 osmo_tdef_get(123, s)	= 1
 osmo_tdef_get(123, ms)	= 1000
 osmo_tdef_get(123, m)	= 1
 osmo_tdef_get(123, custom-unit)	= 1
+osmo_tdef_get(123, us)	= 1000000
 
 test_tdef_get_nonexisting()
 osmo_tdef_get(tdefs, 5, s, 999)	= 999
 osmo_tdef_get(tdefs, 5, ms, 999)	= 999
 osmo_tdef_get(tdefs, 5, m, 999)	= 999
 osmo_tdef_get(tdefs, 5, custom-unit, 999)	= 999
+osmo_tdef_get(tdefs, 5, us, 999)	= 999
 
 test_tdef_set_and_get()
 setting 7 = 42
@@ -99,24 +123,28 @@
 osmo_tdef_get(7, s)	= 42
 osmo_tdef_get(7, m)	= 1
 osmo_tdef_get(7, custom-unit)	= 42
+osmo_tdef_get(7, us)	= 42000000
 setting 7 = 420
 T7=420s(def=50)
 osmo_tdef_get(7, ms)	= 420000
 osmo_tdef_get(7, s)	= 420
 osmo_tdef_get(7, m)	= 7
 osmo_tdef_get(7, custom-unit)	= 420
+osmo_tdef_get(7, us)	= 420000000
 setting 7 = 10 (ERANGE)
 T7=420s(def=50)
 osmo_tdef_get(7, ms)	= 420000
 osmo_tdef_get(7, s)	= 420
 osmo_tdef_get(7, m)	= 7
 osmo_tdef_get(7, custom-unit)	= 420
+osmo_tdef_get(7, us)	= 420000000
 setting 7 = 900 (ERANGE)
 T7=420s(def=50)
 osmo_tdef_get(7, ms)	= 420000
 osmo_tdef_get(7, s)	= 420
 osmo_tdef_get(7, m)	= 7
 osmo_tdef_get(7, custom-unit)	= 420
+osmo_tdef_get(7, us)	= 420000000
 setting 23 = 50 (EEXIST)
 resetting
 T7=50s