diff --git a/src/Makefile.am b/src/Makefile.am
index 7a6f464..74bdb21 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -8,7 +8,7 @@
 lib_LTLIBRARIES = libosmocore.la
 
 libosmocore_la_LIBADD = $(BACKTRACE_LIB) $(TALLOC_LIBS)
-libosmocore_la_SOURCES = timer.c select.c signal.c msgb.c bits.c \
+libosmocore_la_SOURCES = timer.c timer_gettimeofday.c select.c signal.c msgb.c bits.c \
 			 bitvec.c bitcomp.c statistics.c fsm.c \
 			 write_queue.c utils.c socket.c \
 			 logging.c logging_syslog.c rate_ctr.c \
diff --git a/src/gb/gprs_bssgp.c b/src/gb/gprs_bssgp.c
index 3ad2f29..1ee942f 100644
--- a/src/gb/gprs_bssgp.c
+++ b/src/gb/gprs_bssgp.c
@@ -603,7 +603,7 @@
 	fc->queue_depth--;
 
 	/* record the time we transmitted this PDU */
-	gettimeofday(&time_now, NULL);
+	osmo_gettimeofday(&time_now, NULL);
 	fc->time_last_pdu = time_now;
 
 	/* call the output callback for this FC instance */
@@ -688,7 +688,7 @@
 
 	/* compute number of centi-seconds that have elapsed since transmitting
 	 * the last PDU (Tc - Tp) */
-	gettimeofday(&time_now, NULL);
+	osmo_gettimeofday(&time_now, NULL);
 	timersub(&time_now, &fc->time_last_pdu, &time_diff);
 	csecs_elapsed = time_diff.tv_sec*100 + time_diff.tv_usec/10000;
 
@@ -747,7 +747,7 @@
 		return fc_enqueue(fc, msg, llc_pdu_len, priv);
 	} else {
 		/* record the time we transmitted this PDU */
-		gettimeofday(&time_now, NULL);
+		osmo_gettimeofday(&time_now, NULL);
 		fc->time_last_pdu = time_now;
 		return fc->out_cb(priv, msg, llc_pdu_len, NULL);
 	}
@@ -766,7 +766,7 @@
 	fc->bucket_leak_rate = bucket_leak_rate;
 	fc->max_queue_depth = max_queue_depth;
 	INIT_LLIST_HEAD(&fc->queue);
-	gettimeofday(&fc->time_last_pdu, NULL);
+	osmo_gettimeofday(&fc->time_last_pdu, NULL);
 }
 
 /* Initialize the Flow Control parameters for a new MS according to
diff --git a/src/gb/gprs_ns.c b/src/gb/gprs_ns.c
index 6879c70..18845d4 100644
--- a/src/gb/gprs_ns.c
+++ b/src/gb/gprs_ns.c
@@ -556,7 +556,7 @@
 	if (osmo_timer_pending(&nsvc->timer))
 		osmo_timer_del(&nsvc->timer);
 
-	gettimeofday(&nsvc->timer_started, NULL);
+	osmo_gettimeofday(&nsvc->timer_started, NULL);
 	nsvc->timer_mode = mode;
 	osmo_timer_schedule(&nsvc->timer, seconds, 0);
 }
@@ -564,7 +564,7 @@
 static int nsvc_timer_elapsed_ms(struct gprs_nsvc *nsvc)
 {
 	struct timeval now, elapsed;
-	gettimeofday(&now, NULL);
+	osmo_gettimeofday(&now, NULL);
 	timersub(&now, &nsvc->timer_started, &elapsed);
 
 	return 1000 * elapsed.tv_sec + elapsed.tv_usec / 1000;
diff --git a/src/logging.c b/src/logging.c
index 8a10133..9e30d5f 100644
--- a/src/logging.c
+++ b/src/logging.c
@@ -44,6 +44,7 @@
 #include <osmocom/core/talloc.h>
 #include <osmocom/core/utils.h>
 #include <osmocom/core/logging.h>
+#include <osmocom/core/timer.h>
 
 #include <osmocom/vty/logging.h>	/* for LOGGING_STR. */
 
@@ -268,7 +269,7 @@
 		if (target->print_ext_timestamp) {
 			struct tm tm;
 			struct timeval tv;
-			gettimeofday(&tv, NULL);
+			osmo_gettimeofday(&tv, NULL);
 			localtime_r(&tv.tv_sec, &tm);
 			ret = snprintf(buf + offset, rem, "%04d%02d%02d%02d%02d%02d%03d ",
 					tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
diff --git a/src/timer.c b/src/timer.c
index 0358b89..10a0b95 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -91,7 +91,7 @@
 {
 	struct timeval current_time;
 
-	gettimeofday(&current_time, NULL);
+	osmo_gettimeofday(&current_time, NULL);
 	timer->timeout.tv_sec = seconds;
 	timer->timeout.tv_usec = microseconds;
 	timeradd(&timer->timeout, &current_time, &timer->timeout);
@@ -143,7 +143,7 @@
 	struct timeval current_time;
 
 	if (!now)
-		gettimeofday(&current_time, NULL);
+		osmo_gettimeofday(&current_time, NULL);
 	else
 		current_time = *now;
 
@@ -193,7 +193,7 @@
 	struct rb_node *node;
 	struct timeval current;
 
-	gettimeofday(&current, NULL);
+	osmo_gettimeofday(&current, NULL);
 
 	node = rb_first(&timer_root);
 	if (node) {
@@ -214,7 +214,7 @@
 	struct osmo_timer_list *this;
 	int work = 0;
 
-	gettimeofday(&current_time, NULL);
+	osmo_gettimeofday(&current_time, NULL);
 
 	INIT_LLIST_HEAD(&timer_eviction_list);
 	for (node = rb_first(&timer_root); node; node = rb_next(node)) {
diff --git a/src/timer_gettimeofday.c b/src/timer_gettimeofday.c
new file mode 100644
index 0000000..81a1598
--- /dev/null
+++ b/src/timer_gettimeofday.c
@@ -0,0 +1,58 @@
+/*
+ * (C) 2016 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Authors: Neels Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+/*! \addtogroup timer
+ *  @{
+ */
+
+/*! \file timer_gettimeofday.c
+ */
+
+#include <stdbool.h>
+#include <sys/time.h>
+
+bool osmo_gettimeofday_override = false;
+struct timeval osmo_gettimeofday_override_time = { 23, 424242 };
+
+/*! \brief shim around gettimeofday to be able to set the time manually.
+ * To override, set osmo_gettimeofday_override == true and set the desired
+ * current time in osmo_gettimeofday_override_time. */
+int osmo_gettimeofday(struct timeval *tv, struct timezone *tz)
+{
+	if (osmo_gettimeofday_override) {
+		*tv = osmo_gettimeofday_override_time;
+		return 0;
+	}
+
+	return gettimeofday(tv, tz);
+}
+
+/*! \brief convenience function to advance the fake time.
+ * Add the given values to osmo_gettimeofday_override_time. */
+void osmo_gettimeofday_override_add(time_t secs, suseconds_t usecs)
+{
+	struct timeval val = { secs, usecs };
+	timeradd(&osmo_gettimeofday_override_time, &val,
+		 &osmo_gettimeofday_override_time);
+}
+
+/*! @} */
diff --git a/src/vty/command.c b/src/vty/command.c
index 483ca80..9d8bf31 100644
--- a/src/vty/command.c
+++ b/src/vty/command.c
@@ -637,7 +637,7 @@
 	struct timeval tv;
 	char *crypt(const char *, const char *);
 
-	gettimeofday(&tv, 0);
+	osmo_gettimeofday(&tv, 0);
 
 	to64(&salt[0], random(), 3);
 	to64(&salt[3], tv.tv_usec, 3);