diff --git a/src/src/PluginStructs/P056_data_struct.cpp b/src/src/PluginStructs/P056_data_struct.cpp
index 3402a7432..d70911504 100644
--- a/src/src/PluginStructs/P056_data_struct.cpp
+++ b/src/src/PluginStructs/P056_data_struct.cpp
@@ -49,7 +49,7 @@ float P056_data_struct::GetPM10_() {
   }
 }
 
-bool P056_data_struct::ReadAverage(float pm25, float pm10) {
+bool P056_data_struct::ReadAverage(float& pm25, float& pm10) {
   if (isInitialized()) {
     return this->SDS->ReadAverage(pm25, pm10);
   } else {
diff --git a/src/src/PluginStructs/P056_data_struct.h b/src/src/PluginStructs/P056_data_struct.h
index 2d408ba16..ac1fa410d 100644
--- a/src/src/PluginStructs/P056_data_struct.h
+++ b/src/src/PluginStructs/P056_data_struct.h
@@ -17,8 +17,8 @@ struct P056_data_struct : public PluginTaskData_base {
   bool  available();
   float GetPM2_5();
   float GetPM10_();
-  bool  ReadAverage(float pm25,
-                    float pm10);
+  bool  ReadAverage(float& pm25,
+                    float& pm10);
   void  SetWorkingPeriod(int minutes);
 
 private: