diff --git a/include/globals.h b/include/globals.h
index 9e8549e5..55ee199e 100644
--- a/include/globals.h
+++ b/include/globals.h
@@ -42,7 +42,7 @@
 #define SCREEN_MODE (0x80)
 
 // I2C bus access control
-#define I2C_MUTEX_LOCK() (xSemaphoreTake(I2Caccess, pdMS_TO_TICKS(10)) == pdTRUE)
+#define I2C_MUTEX_LOCK() (xSemaphoreTake(I2Caccess, pdMS_TO_TICKS(2000)) == pdTRUE)
 #define I2C_MUTEX_UNLOCK() (xSemaphoreGive(I2Caccess))
 
 // Struct holding devices's runtime configuration
diff --git a/src/lorawan.cpp b/src/lorawan.cpp
index 07d893c8..58baf00d 100644
--- a/src/lorawan.cpp
+++ b/src/lorawan.cpp
@@ -510,12 +510,12 @@ void IRAM_ATTR user_request_network_time_callback(void *pVoidUserUTCTime,
   // begin of time critical section
 
   // lock I2C bus and application irq to ensure accurate timing
+  mask_user_IRQ();
   if (!I2C_MUTEX_LOCK()) {
     ESP_LOGW(TAG, "[%0.3f] Timesync handshake error: i2c bus locking failed",
              millis() / 1000.0);
     goto finish; // failure
   }
-  mask_user_IRQ();
 
   // Update userUTCTime, considering the difference between the GPS and UTC
   // time, and the leap seconds until year 2019
diff --git a/src/timesync.cpp b/src/timesync.cpp
index 00d80bcf..35fb8c84 100644
--- a/src/timesync.cpp
+++ b/src/timesync.cpp
@@ -64,7 +64,7 @@ void process_timesync_req(void *taskparameter) {
 
     // wait until we are joined if we are not
     while (!LMIC.devaddr) {
-      vTaskDelay(1000);
+      vTaskDelay(3000);
     }
 
     // collect timestamp samples
@@ -111,12 +111,12 @@ void process_timesync_req(void *taskparameter) {
     } // end of for loop to collect timestamp samples
 
     // lock I2C bus and application irq to ensure accurate timing
+    mask_user_IRQ();
     if (!I2C_MUTEX_LOCK()) {
       ESP_LOGW(TAG, "[%0.3f] Timesync handshake error: i2c bus locking failed",
                millis() / 1000.0);
       goto finish; // failure
     }
-    mask_user_IRQ();
 
     // average time offset over all collected diffs
     time_offset_ms /= TIME_SYNC_SAMPLES;