diff --git a/DCC.cpp b/DCC.cpp
index b969a8c..aec1662 100644
--- a/DCC.cpp
+++ b/DCC.cpp
@@ -268,14 +268,9 @@ bool DCC::setFn( int cab, int16_t functionNumber, bool on) {
 
 // Flip function state (used from withrottle protocol)
 void DCC::changeFn( int cab, int16_t functionNumber) {
-  if (cab<=0 || functionNumber>31) return;
-  auto slot=lookupSpeedTable(cab);
-  unsigned long funcmask = (1UL<<functionNumber);
-  slot->functions ^= funcmask;
-  if (functionNumber <= 28) {
-    updateGroupflags(slot->groupFlags, functionNumber);
-  }
-  CommandDistributor::broadcastLoco(slot);
+  auto currentValue=getFn(cab,functionNumber);
+  if (currentValue<0) return;  // function not valid for change  
+  setFn(cab,functionNumber, currentValue?false:true);
 }
 
 // Report function state (used from withrottle protocol)
diff --git a/version.h b/version.h
index 8fd1185..3b96de1 100644
--- a/version.h
+++ b/version.h
@@ -3,7 +3,8 @@
 
 #include "StringFormatter.h"
 
-#define VERSION "5.5.8"
+#define VERSION "5.5.9"
+// 5.5.9  = (5.4.3) fix changeFn for functions 29..31
 // 5.5.8  - EXSensorCam clean up to match other filters and
 //        - avoid need for config.h settings
 //        - Test: IO_I2CDFPlayer.h inserted 10mS deleay in Init_SC16IS752() just after soft-reset for board with 1.8432 Mhz xtal