diff --git a/drivers/Timer.cpp b/drivers/Timer.cpp
index 2de1eed0b6..a2e9194dea 100644
--- a/drivers/Timer.cpp
+++ b/drivers/Timer.cpp
@@ -31,7 +31,7 @@ Timer::Timer(const ticker_data_t *data) : _running(), _start(), _time(), _ticker
 void Timer::start() {
     core_util_critical_section_enter();
     if (!_running) {
-        _start = ticker_read(_ticker_data);
+        _start = ticker_read_us(_ticker_data);
         _running = 1;
     }
     core_util_critical_section_exit();
@@ -46,24 +46,31 @@ void Timer::stop() {
 
 int Timer::read_us() {
     core_util_critical_section_enter();
-    int time = _time + slicetime();
+    us_timestamp_t time = _time + slicetime();
     core_util_critical_section_exit();
     return time;
 }
 
 float Timer::read() {
-    return (float)read_us() / 1000000.0f;
+    core_util_critical_section_enter();
+    us_timestamp_t time = _time + slicetime();
+    core_util_critical_section_exit();
+    time = time / 1000;
+    return (float)read_ms() / 1000.0f;
 }
 
 int Timer::read_ms() {
-    return read_us() / 1000;
+    core_util_critical_section_enter();
+    us_timestamp_t time = _time + slicetime();
+    core_util_critical_section_exit();
+    return time / 1000;    
 }
 
-int Timer::slicetime() {
+us_timestamp_t Timer::slicetime() {
     core_util_critical_section_enter();
-    int ret = 0;
+    us_timestamp_t ret = 0;
     if (_running) {
-        ret = ticker_read(_ticker_data) - _start;
+        ret = ticker_read_us(_ticker_data) - _start;
     }
     core_util_critical_section_exit();
     return ret;
@@ -71,7 +78,7 @@ int Timer::slicetime() {
 
 void Timer::reset() {
     core_util_critical_section_enter();
-    _start = ticker_read(_ticker_data);
+    _start = ticker_read_us(_ticker_data);
     _time = 0;
     core_util_critical_section_exit();
 }
diff --git a/drivers/Timer.h b/drivers/Timer.h
index 51ed940966..729e71b314 100644
--- a/drivers/Timer.h
+++ b/drivers/Timer.h
@@ -83,10 +83,10 @@ public:
     operator float();
 
 protected:
-    int slicetime();
-    int _running;          // whether the timer is running
-    unsigned int _start;   // the start time of the latest slice
-    int _time;             // any accumulated time from previous slices
+    us_timestamp_t slicetime();
+    int _running;            // whether the timer is running
+    us_timestamp_t _start;   // the start time of the latest slice
+    us_timestamp_t _time;    // any accumulated time from previous slices
     const ticker_data_t *_ticker_data;
 };