diff --git a/src/modules/RF69/RF69.cpp b/src/modules/RF69/RF69.cpp
index d484a9eb..8671e137 100644
--- a/src/modules/RF69/RF69.cpp
+++ b/src/modules/RF69/RF69.cpp
@@ -712,7 +712,7 @@ int16_t RF69::setSyncWord(const uint8_t* syncWord, size_t len, uint8_t maxErrBit
   RADIOLIB_ASSERT(state);
 
   // set the length
-  state = this->mod->SPIsetRegValue(RADIOLIB_RF69_REG_SYNC_CONFIG, len-1, 5, 3);
+  state = this->mod->SPIsetRegValue(RADIOLIB_RF69_REG_SYNC_CONFIG, (len-1)<<3, 5, 3);
 
   // set sync word register
   this->mod->SPIwriteRegisterBurst(RADIOLIB_RF69_REG_SYNC_VALUE_1, syncWord, len);