diff --git a/TommyPROM/PromDevice27.cpp b/TommyPROM/PromDevice27.cpp
index 3e29e41..1cf7e2b 100644
--- a/TommyPROM/PromDevice27.cpp
+++ b/TommyPROM/PromDevice27.cpp
@@ -85,6 +85,7 @@ bool PromDevice27::burnByte(byte value, uint32_t address)
     bool status = false;
     unsigned writeCount = 0;
 
+    byte data = 0;
     disableOutput();
     disableWrite();
     enableChip();