diff --git a/DCCRMT.h b/DCCRMT.h
index 33257a0..3a20027 100644
--- a/DCCRMT.h
+++ b/DCCRMT.h
@@ -44,6 +44,12 @@ class RMTChannel {
       return true;
     return dataReady;
   };
+  inline void waitForDataCopy() {
+    while(1) { // do nothing and wait for interrupt clearing dataReady to happen
+      if (dataReady == false)
+	break;
+    }
+  };
   inline uint32_t packetCount() { return packetCounter; };
   
  private:
diff --git a/DCCWaveformRMT.cpp b/DCCWaveformRMT.cpp
index aa3c223..4c10ceb 100644
--- a/DCCWaveformRMT.cpp
+++ b/DCCWaveformRMT.cpp
@@ -70,7 +70,11 @@ void DCCWaveform::begin() {
 
 void DCCWaveform::schedulePacket(const byte buffer[], byte byteCount, byte repeats) {
   if (byteCount > MAX_PACKET_SIZE) return; // allow for chksum
+  RMTChannel *rmtchannel = (isMainTrack ? rmtMainChannel : rmtProgChannel);
+  if (rmtchannel == NULL)
+    return; // no idea to prepare packet if we can not send it anyway
   
+  rmtchannel->waitForDataCopy(); // blocking wait so we can write into buffer
   byte checksum = 0;
   for (byte b = 0; b < byteCount; b++) {
     checksum ^= buffer[b];
@@ -88,13 +92,7 @@ void DCCWaveform::schedulePacket(const byte buffer[], byte byteCount, byte repea
   {
     int ret = 0;
     do {
-      if(isMainTrack) {
-	if (rmtMainChannel != NULL)
-	  ret = rmtMainChannel->RMTfillData(pendingPacket, pendingLength, pendingRepeats);
-      } else {
-	if (rmtProgChannel != NULL)
-	  ret = rmtProgChannel->RMTfillData(pendingPacket, pendingLength, pendingRepeats);
-      }
+      ret = rmtchannel->RMTfillData(pendingPacket, pendingLength, pendingRepeats);
     } while(ret > 0);
   }
 }
diff --git a/GITHUB_SHA.h b/GITHUB_SHA.h
index 1024a4f..b1c3d8f 100644
--- a/GITHUB_SHA.h
+++ b/GITHUB_SHA.h
@@ -1 +1 @@
-#define GITHUB_SHA "devel-202501092043Z"
+#define GITHUB_SHA "devel-202501171827Z"
diff --git a/version.h b/version.h
index b15e3d2..2ba389b 100644
--- a/version.h
+++ b/version.h
@@ -3,7 +3,8 @@
 
 #include "StringFormatter.h"
 
-#define VERSION "5.5.6"
+#define VERSION "5.5.7"
+// 5.5.7  - ESP32 bugfix packet buffer race (as 5.4.1)
 // 5.5.6  - Fix ESP32 build bug caused by include reference loop
 // 5.5.5  - Railcom implementation with IO_I2CRailcom driver
 //        - response analysis and block management.