diff --git a/i2c.cpp b/i2c.cpp
index 76e3e93..dfbb654 100644
--- a/i2c.cpp
+++ b/i2c.cpp
@@ -104,7 +104,7 @@
     auto step = &req->step[req->numSteps++];
 
     // Deserialize request step header bytes.
-    uint8_t devAndDir = data[stepHeaderDevAndDir];
+    uint8_t devAndDir = stepHdr[stepHeaderDevAndDir];
     uint8_t stepFlags = stepHdr[stepHeaderFlags];
     step->length = stepHdr[stepHeaderParm];
     bytesLeft -= stepHeaderLen;