diff --git a/src/modules/Si443x/Si443x.cpp b/src/modules/Si443x/Si443x.cpp
index c250dfdd..f555c21f 100644
--- a/src/modules/Si443x/Si443x.cpp
+++ b/src/modules/Si443x/Si443x.cpp
@@ -199,6 +199,9 @@ int16_t Si443x::receiveDirect() {
 }
 
 int16_t Si443x::packetMode() {
+  int16_t state = _mod->SPIsetRegValue(SI443X_REG_MODULATION_MODE_CONTROL_2, SI443X_MODULATION_FSK, 1, 0);
+  RADIOLIB_ASSERT(state);
+
   return(_mod->SPIsetRegValue(SI443X_REG_MODULATION_MODE_CONTROL_2, SI443X_TX_DATA_SOURCE_FIFO, 5, 4));
 }