diff --git a/cores/arduino/WInterrupts.c b/cores/arduino/WInterrupts.c
index 9c4ad1a..93a9353 100644
--- a/cores/arduino/WInterrupts.c
+++ b/cores/arduino/WInterrupts.c
@@ -6,8 +6,6 @@
 #include "WInterrupts.h"
 #include "wiring_LL.h" 
 
-extern void ErrorMsgHandler(const char * msg);
-
 typedef void (*voidFuncPtr)(void);
 
 // empty irq handler
diff --git a/cores/arduino/WString.cpp b/cores/arduino/WString.cpp
index 1f06d2b..401c657 100644
--- a/cores/arduino/WString.cpp
+++ b/cores/arduino/WString.cpp
@@ -19,7 +19,7 @@
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
-#pragma GCC diagnostic ignored "-Wrestrict" // для GCC и Clang
+#pragma GCC diagnostic ignored "-Wrestrict" // for GCC and Clang
 
 #include "WString.h"
 #include "itoa.h"
diff --git a/cores/arduino/board.cpp b/cores/arduino/board.cpp
index 04bfa4c..876cb87 100644
--- a/cores/arduino/board.cpp
+++ b/cores/arduino/board.cpp
@@ -30,13 +30,15 @@ void post_init(void)
 }
 
 // --------------------- other --------------------- // 
-// print text if Serial is enabled
+volatile bool use_error_messages = true;
+// print error message to Serial
 extern "C" void ErrorMsgHandler(const char * msg)
 {
-#ifdef HardwareSerial_h
-    if(Serial)
-        Serial.println(msg);
-#endif
+    // function works if Serial is used in sketch and user doesn't turn it off
+    #ifdef HardwareSerial_h         
+        if(use_error_messages&&Serial)
+            Serial.println(msg);
+    #endif
 }
 
 
diff --git a/cores/arduino/board.h b/cores/arduino/board.h
index ad1ae06..61599a0 100644
--- a/cores/arduino/board.h
+++ b/cores/arduino/board.h
@@ -1,6 +1,10 @@
 #ifndef _BOARD_H_
 #define _BOARD_H_
 
+extern volatile bool use_error_messages;
+#define DISABLE_ERROR_MESSAGES()    (use_error_messages = false)
+#define ENABLE_ERROR_MESSAGES()     (use_error_messages = true)
+
 // functions for init called before and after setup()
 void pre_init(void) ;
 void post_init(void);
diff --git a/cores/arduino/wiring_analog.c b/cores/arduino/wiring_analog.c
index 8af6dfe..c7e5c35 100644
--- a/cores/arduino/wiring_analog.c
+++ b/cores/arduino/wiring_analog.c
@@ -8,7 +8,6 @@ extern "C" {
 #include "mik32_hal_gpio.h"
 #include "mik32_hal_timer32.h"
 
-extern void ErrorMsgHandler(const char * msg);
 
 // -------------------------- Analog read -------------------------- //
 #define ADC_SAMPLES_QTY           10  // samples quantity for averaging adc results
diff --git a/cores/arduino/wiring_digital.c b/cores/arduino/wiring_digital.c
index 9f82c27..1894c4f 100644
--- a/cores/arduino/wiring_digital.c
+++ b/cores/arduino/wiring_digital.c
@@ -24,8 +24,6 @@
 extern "C" {
 #endif
 
-extern void ErrorMsgHandler(const char * msg);
-
 // initialization
 void pinMode(uint32_t PinNumber, uint32_t PinMode)
 {
diff --git a/variants/standart/variant.c b/variants/standart/variant.c
index ed0f3b6..a54ee4d 100644
--- a/variants/standart/variant.c
+++ b/variants/standart/variant.c
@@ -16,14 +16,6 @@
 #include "wiring_analog.h"
 #include "wiring_LL.h" 
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-void ErrorMsgHandler(const char * msg);
-#ifdef __cplusplus
-}
-#endif
-
 bool spiNssPinIsBlocked = false;
 
 // list of pin numbers from both ports with pins inside the port