diff --git a/src/main/common/filter.c b/src/main/common/filter.c
index cd44aa1b5..f3582f213 100644
--- a/src/main/common/filter.c
+++ b/src/main/common/filter.c
@@ -46,11 +46,12 @@ void pt1FilterInit(pt1Filter_t *filter, uint8_t f_cut, float dT)
 {
     filter->RC = 1.0f / ( 2.0f * M_PI_FLOAT * f_cut );
     filter->dT = dT;
+    filter->k = filter->dT / (filter->RC + filter->dT);
 }
 
 float pt1FilterApply(pt1Filter_t *filter, float input)
 {
-    filter->state = filter->state + filter->dT / (filter->RC + filter->dT) * (input - filter->state);
+    filter->state = filter->state + filter->k * (input - filter->state);
     return filter->state;
 }
 
@@ -60,9 +61,10 @@ float pt1FilterApply4(pt1Filter_t *filter, float input, uint8_t f_cut, float dT)
     if (!filter->RC) {
         filter->RC = 1.0f / ( 2.0f * M_PI_FLOAT * f_cut );
         filter->dT = dT;
+        filter->k = filter->dT / (filter->RC + filter->dT);
     }
 
-    filter->state = filter->state + filter->dT / (filter->RC + filter->dT) * (input - filter->state);
+    filter->state = filter->state + filter->k * (input - filter->state);
 
     return filter->state;
 }
diff --git a/src/main/common/filter.h b/src/main/common/filter.h
index 35b5ca8f1..4d86bc431 100644
--- a/src/main/common/filter.h
+++ b/src/main/common/filter.h
@@ -25,6 +25,7 @@
 
 typedef struct pt1Filter_s {
     float state;
+    float k;
     float RC;
     float dT;
 } pt1Filter_t;