diff --git a/t/.gitignore b/t/.gitignore
index 20217f0d0..e8f9c24b2 100644
--- a/t/.gitignore
+++ b/t/.gitignore
@@ -73,3 +73,4 @@ janus.c
 websocket.c
 test-stats
 ssllib.c
+time-fudge-preload.so
diff --git a/t/Makefile b/t/Makefile
index 160f3a313..2bcd97794 100644
--- a/t/Makefile
+++ b/t/Makefile
@@ -101,7 +101,7 @@ TESTS+=		test-amr-decode test-amr-encode
 endif
 endif
 
-ADD_CLEAN=	tests-preload.so $(TESTS)
+ADD_CLEAN=	tests-preload.so time-fudge-preload.so $(TESTS)
 
 ifeq ($(with_transcoding),yes)
 all-tests:	unit-tests daemon-tests
@@ -273,6 +273,9 @@ PRELOAD_LIBS += -ldl
 tests-preload.so:	tests-preload.c
 	$(CC) $(PRELOAD_CFLAGS) -o $@ -shared -fPIC $< $(LDFLAGS) $(PRELOAD_LIBS)
 
+time-fudge-preload.so:	time-fudge-preload.c
+	$(CC) $(PRELOAD_CFLAGS) -o $@ -shared -fPIC $< $(LDFLAGS) $(PRELOAD_LIBS)
+
 spandsp_send_fax_pcm.c:	spandsp_logging.h
 spandsp_send_fax_t38.c:	spandsp_logging.h
 spandsp_recv_fax_t38.c:	spandsp_logging.h
diff --git a/t/time-fudge-preload.c b/t/time-fudge-preload.c
new file mode 100644
index 000000000..1e24d5f66
--- /dev/null
+++ b/t/time-fudge-preload.c
@@ -0,0 +1,48 @@
+#include <dlfcn.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <stdlib.h>
+
+static inline long long timeval_us(const struct timeval *t) {
+        return (long long) ((long long) t->tv_sec * 1000000LL) + t->tv_usec;
+}
+static inline void timeval_from_us(struct timeval *t, long long us) {
+        t->tv_sec = us/1000000LL;
+        t->tv_usec = us%1000000LL;
+}
+static inline long long timespec_ns(const struct timespec *t) {
+        return (long long) ((long long) t->tv_sec * 1000000000LL) + t->tv_nsec;
+}
+static inline void timespec_from_ns(struct timespec *t, long long ns) {
+        t->tv_sec = ns/1000000000LL;
+        t->tv_nsec = ns%1000000000LL;
+}
+static long long offset = 0;
+int gettimeofday(struct timeval *restrict tv, void *restrict tz) {
+	__typeof__ (gettimeofday) *fn = dlsym(RTLD_NEXT, "gettimeofday");
+	int ret = fn(tv, tz);
+	if (ret)
+		return ret;
+	long r = random();
+	if (r < ((1L<<31) / 100)) {
+		// 1% chance
+		long long add = random() & 0xffff;
+		offset += add;
+		fprintf(stderr, "moving clock forward by %lli us\n", add);
+	}
+	long long tvs = timeval_us(tv);
+	tvs += offset;
+	timeval_from_us(tv, tvs);
+	return ret;
+}
+int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, const struct timespec *abstime) {
+	__typeof__ (pthread_cond_timedwait) *fn = dlsym(RTLD_NEXT, "pthread_cond_timedwait");
+	if (!abstime)
+		return fn(cond, mutex, abstime);
+	struct timespec tn;
+	long long ns = timespec_ns(abstime);
+	ns -= offset * 1000LL;
+	timespec_from_ns(&tn, ns);
+	return fn(cond, mutex, &tn);
+}