diff --git a/src/emulator/decode.c b/src/emulator/decode.c
index 3fbaaa6..78dcbac 100644
--- a/src/emulator/decode.c
+++ b/src/emulator/decode.c
@@ -13,6 +13,8 @@
 #include "decode.h"
 #include "../shared/binary_util.h"
 
+// Macro that calls getBit() for a bitfield whose constants follow the format
+// FIELDNAME_LSB and FIELDNAME_MSB, storing the result in the variable wrd
 #define getField(fieldname) getBits(wrd, fieldname##_LSB, fieldname##_MSB)
 
 /************************************