diff --git a/src/protocols/PhysicalLayer/PhysicalLayer.cpp b/src/protocols/PhysicalLayer/PhysicalLayer.cpp
index c872c724..78acfebb 100644
--- a/src/protocols/PhysicalLayer/PhysicalLayer.cpp
+++ b/src/protocols/PhysicalLayer/PhysicalLayer.cpp
@@ -123,10 +123,11 @@ int16_t PhysicalLayer::standby(uint8_t mode) {
   return(RADIOLIB_ERR_UNSUPPORTED);
 }
 
-int16_t PhysicalLayer::startReceive(uint32_t timeout, uint16_t irqFlags, uint16_t irqMask) {
+int16_t PhysicalLayer::startReceive(uint32_t timeout, uint16_t irqFlags, uint16_t irqMask, size_t len) {
   (void)timeout;
   (void)irqFlags;
   (void)irqMask;
+  (void)len;
   return(RADIOLIB_ERR_UNSUPPORTED);
 }
 
diff --git a/src/protocols/PhysicalLayer/PhysicalLayer.h b/src/protocols/PhysicalLayer/PhysicalLayer.h
index c53b7c41..915faf45 100644
--- a/src/protocols/PhysicalLayer/PhysicalLayer.h
+++ b/src/protocols/PhysicalLayer/PhysicalLayer.h
@@ -106,17 +106,19 @@ class PhysicalLayer {
     virtual int16_t standby(uint8_t mode);
 
     /*!
-      \brief Interrupt-driven receive method. DIO1 will be activated when full packet is received.
+      \brief Interrupt-driven receive method. A DIO pin will be activated when full packet is received. Must be implemented in module class.
 
-      \param timeout Raw timeout value.
+      \param timeout Raw timeout value. Some modules use this argument to specify operation mode (single vs. continuous receive).
 
       \param irqFlags Sets the IRQ flags.
 
-      \param irqMask Sets the mask of IRQ flags that will trigger DIO1.
+      \param irqMask Sets the mask of IRQ flags that will trigger the DIO pin.
+
+      \param len Packet length, needed for some modules under special circumstances (e.g. LoRa implicit header mode).
 
       \returns \ref status_codes
     */
-    virtual int16_t startReceive(uint32_t timeout = 0, uint16_t irqFlags = 0, uint16_t irqMask = 0);
+    virtual int16_t startReceive(uint32_t timeout, uint16_t irqFlags, uint16_t irqMask, size_t len);
 
     /*!
       \brief Binary receive method. Must be implemented in module class.