diff --git a/lib/Hoymiles/src/HoymilesRadio_CMT.cpp b/lib/Hoymiles/src/HoymilesRadio_CMT.cpp
index e8e193b..71b8d70 100644
--- a/lib/Hoymiles/src/HoymilesRadio_CMT.cpp
+++ b/lib/Hoymiles/src/HoymilesRadio_CMT.cpp
@@ -14,6 +14,12 @@
 // offset from initalized CMT base frequency to Hoy base frequency in channels
 #define CMT_BASE_CH_OFFSET860 ((860000000 - HOY_BASE_FREQ) / CMT2300A_ONE_STEP_SIZE / FH_OFFSET)
 
+// frequency can not be lower than actual initailized base freq
+#define CMT_MIN_FREQ_KHZ ((HOY_BASE_FREQ + (CMT_BASE_CH_OFFSET860 >= 1 ? CMT_BASE_CH_OFFSET860 : 1) * CMT2300A_ONE_STEP_SIZE * FH_OFFSET) / 1000)
+
+// =923500, 0xFF does not work
+#define CMT_MAX_FREQ_KHZ ((HOY_BASE_FREQ + 0xFE * CMT2300A_ONE_STEP_SIZE * FH_OFFSET) / 1000)
+
 String HoymilesRadio_CMT::cmtChToFreq(const uint8_t channel)
 {
     return String((HOY_BASE_FREQ + (CMT_BASE_CH_OFFSET860 + channel) * FH_OFFSET * CMT2300A_ONE_STEP_SIZE) / 1000000.0, 2) + " MHz";
@@ -34,11 +40,9 @@ uint8_t HoymilesRadio_CMT::cmtFreqToChan(const String& func_name, const String&
             func_name.c_str(), var_name.c_str(), freq_kHz / 1000.0);
         return 0xFF; // ERROR
     }
-    const uint32_t min_Freq_kHz = (HOY_BASE_FREQ + (CMT_BASE_CH_OFFSET860 >= 1 ? CMT_BASE_CH_OFFSET860 : 1) * CMT2300A_ONE_STEP_SIZE * FH_OFFSET) / 1000; // frequency can not be lower than actual initailized base freq
-    const uint32_t max_Freq_kHz = (HOY_BASE_FREQ + 0xFE * CMT2300A_ONE_STEP_SIZE * FH_OFFSET) / 1000; // =923500, 0xFF does not work
-    if (freq_kHz < min_Freq_kHz || freq_kHz > max_Freq_kHz) {
+    if (freq_kHz < CMT_MIN_FREQ_KHZ || freq_kHz > CMT_MAX_FREQ_KHZ) {
         Hoymiles.getMessageOutput()->printf("%s %s %.2f MHz is out of Hoymiles/CMT range! (%.2f MHz - %.2f MHz)\r\n",
-            func_name.c_str(), var_name.c_str(), freq_kHz / 1000.0, min_Freq_kHz / 1000.0, max_Freq_kHz / 1000.0);
+            func_name.c_str(), var_name.c_str(), freq_kHz / 1000.0, CMT_MIN_FREQ_KHZ / 1000.0, CMT_MAX_FREQ_KHZ / 1000.0);
         return 0xFF; // ERROR
     }
     if (freq_kHz < 863000 || freq_kHz > 870000) {
@@ -453,6 +457,16 @@ bool HoymilesRadio_CMT::isConnected()
     return _radio->isChipConnected();
 }
 
+uint32_t HoymilesRadio_CMT::getMinFrequency()
+{
+    return CMT_MIN_FREQ_KHZ;
+}
+
+uint32_t HoymilesRadio_CMT::getMaxFrequency()
+{
+    return CMT_MAX_FREQ_KHZ;
+}
+
 void ARDUINO_ISR_ATTR HoymilesRadio_CMT::handleInt1()
 {
     _packetSent = true;
diff --git a/lib/Hoymiles/src/HoymilesRadio_CMT.h b/lib/Hoymiles/src/HoymilesRadio_CMT.h
index f4218c1..a2fe137 100644
--- a/lib/Hoymiles/src/HoymilesRadio_CMT.h
+++ b/lib/Hoymiles/src/HoymilesRadio_CMT.h
@@ -51,6 +51,9 @@ public:
 
     bool isConnected();
 
+    static uint32_t getMinFrequency();
+    static uint32_t getMaxFrequency();
+
 private:
     void ARDUINO_ISR_ATTR handleInt1();
     void ARDUINO_ISR_ATTR handleInt2();
diff --git a/src/WebApi_dtu.cpp b/src/WebApi_dtu.cpp
index c89fb78..fc4dade 100644
--- a/src/WebApi_dtu.cpp
+++ b/src/WebApi_dtu.cpp
@@ -129,11 +129,14 @@ void WebApiDtuClass::onDtuAdminPost(AsyncWebServerRequest* request)
         return;
     }
 
-    if (root["cmt_frequency"].as<uint32_t>() < 860000 || root["cmt_frequency"].as<uint32_t>() > 923000 || root["cmt_frequency"].as<uint32_t>() % 250 > 0) {
+    if (root["cmt_frequency"].as<uint32_t>() < Hoymiles.getRadioCmt()->getMinFrequency()
+        || root["cmt_frequency"].as<uint32_t>() > Hoymiles.getRadioCmt()->getMaxFrequency()
+        || root["cmt_frequency"].as<uint32_t>() % 250 > 0) {
+
         retMsg["message"] = "Invalid CMT frequency setting!";
         retMsg["code"] = WebApiError::DtuInvalidCmtFrequency;
-        retMsg["param"]["min"] = 860000;
-        retMsg["param"]["max"] = 923000;
+        retMsg["param"]["min"] = Hoymiles.getRadioCmt()->getMinFrequency();
+        retMsg["param"]["max"] = Hoymiles.getRadioCmt()->getMaxFrequency();
         response->setLength();
         request->send(response);
         return;