diff --git a/libs/core/input.ts b/libs/core/input.ts
index 05f39e89..20b1dd67 100644
--- a/libs/core/input.ts
+++ b/libs/core/input.ts
@@ -13,6 +13,7 @@ namespace sensors.internal {
 
         control.runInBackground(() => {
             let prev = query()
+            changeHandler(prev, prev)
             while (true) {
                 loops.pause(periodMs)
                 let curr = query()
@@ -183,7 +184,7 @@ namespace sensors.internal {
         Low = 3,
     }
 
-    export class ThresholdDetector {        
+    export class ThresholdDetector {
         public id: number;
         private min: number;
         private max: number;
diff --git a/libs/core/linux.cpp b/libs/core/linux.cpp
index 5e7bcfa4..391f7373 100644
--- a/libs/core/linux.cpp
+++ b/libs/core/linux.cpp
@@ -397,6 +397,10 @@ static void runPoller(Thread *thr) {
     // note that this is run without the user mutex held - it should not modify any state!
     TValue prev = pxt::runAction0(query);
 
+    startUser();
+    pxt::runAction2(thr->act, prev, prev);
+    stopUser();
+
     while (true) {
         sleep_core_us(us);
         if (paniced)