diff --git a/src/devices/mixing.cpp b/src/devices/mixing.cpp
index fe7c09b8b..995045676 100644
--- a/src/devices/mixing.cpp
+++ b/src/devices/mixing.cpp
@@ -103,7 +103,7 @@ void Mixing::show_values(uuid::console::Shell & shell) {
 // publish values via MQTT
 // ideally we should group up all the mixing units together into a nested JSON but for now we'll send them individually
 void Mixing::publish_values() {
-    DynamicJsonDocument doc(EMSESP_MAX_JSON_SIZE_SMALL);
+    StaticJsonDocument<EMSESP_MAX_JSON_SIZE_SMALL> doc;
 
     switch (type_) {
     case Type::HC:
diff --git a/src/mqtt.h b/src/mqtt.h
index daf26098e..6c8ced445 100644
--- a/src/mqtt.h
+++ b/src/mqtt.h
@@ -37,9 +37,9 @@
 
 using uuid::console::Shell;
 
-#define EMSESP_MAX_JSON_SIZE_SMALL 200  // for smaller json docs
-#define EMSESP_MAX_JSON_SIZE_MEDIUM 800 // for smaller json docs from ems devices
-#define EMSESP_MAX_JSON_SIZE_LARGE 1500 // for large json docs from ems devices, like boiler or thermostat data
+#define EMSESP_MAX_JSON_SIZE_SMALL 200  // for smaller json docs when using StaticJsonDocument
+#define EMSESP_MAX_JSON_SIZE_MEDIUM 800 // for smaller json docs from ems devices, when using StaticJsonDocument
+#define EMSESP_MAX_JSON_SIZE_LARGE 1500 // for large json docs from ems devices, like boiler or thermostat data. Using DynamicJsonDocument
 
 namespace emsesp {