diff --git a/src/GPS.cpp b/src/GPS.cpp
index c89a55368..6b89e6324 100644
--- a/src/GPS.cpp
+++ b/src/GPS.cpp
@@ -70,7 +70,7 @@ uint32_t GPS::getValidTime()
     return timeSetFromGPS ? getTime() : 0;
 }
 
-uint32_t GPS::doTask()
+void GPS::doTask()
 {
 #ifdef GPS_RX_PIN
     // Consume all characters that have arrived
@@ -111,7 +111,7 @@ uint32_t GPS::doTask()
     }
 
     // Once we have sent a location we only poll the GPS rarely, otherwise check back every 100ms until we have something over the serial
-    return hasValidLocation ? 30 * 1000 : 100;
+    setPeriod(hasValidLocation ? 30 * 1000 : 100);
 }
 
 String GPS::getTimeStr()
diff --git a/src/GPS.h b/src/GPS.h
index 1a2c82ad9..9ff98cca3 100644
--- a/src/GPS.h
+++ b/src/GPS.h
@@ -27,7 +27,7 @@ public:
 
     virtual void loop();
 
-    virtual uint32_t doTask();
+    virtual void doTask();
 
     /// If we haven't yet set our RTC this boot, set it from a GPS derived time
     void perhapsSetRTC(const struct timeval *tv);
diff --git a/src/Periodic.h b/src/Periodic.h
index 92d66241f..2081a5065 100644
--- a/src/Periodic.h
+++ b/src/Periodic.h
@@ -18,5 +18,5 @@ public:
 
 protected:
 
-  uint32_t doTask();
+  void doTask();
 };
diff --git a/src/PeriodicTask.cpp b/src/PeriodicTask.cpp
index bb46d1ce2..b9410c69e 100644
--- a/src/PeriodicTask.cpp
+++ b/src/PeriodicTask.cpp
@@ -12,8 +12,12 @@ void PeriodicTask::loop()
     if (period && (now - lastMsec) >= period)
     {
         lastMsec = now;
-        period = doTask();
+        doTask();
     }
 }
 
-  uint32_t Periodic::doTask() { return callback(); }
\ No newline at end of file
+void Periodic::doTask()
+{
+    uint32_t p = callback();
+    setPeriod(p);
+}
\ No newline at end of file
diff --git a/src/PeriodicTask.h b/src/PeriodicTask.h
index 5ac90e29a..59659e2d4 100644
--- a/src/PeriodicTask.h
+++ b/src/PeriodicTask.h
@@ -25,6 +25,9 @@ public:
     /// call this from loop
     virtual void loop();
 
+    /// Set a new period in msecs (can be called from doTask or elsewhere and the scheduler will cope)
+    void setPeriod(uint32_t p) { period = p; }
+
 protected: 
-    virtual uint32_t doTask() = 0;
+    virtual void doTask() = 0;
 };