diff --git a/src/compiler/codegen/arm/ArmLIR.h b/src/compiler/codegen/arm/ArmLIR.h
index e4e9eb8..cafc993 100644
--- a/src/compiler/codegen/arm/ArmLIR.h
+++ b/src/compiler/codegen/arm/ArmLIR.h
@@ -735,7 +735,7 @@
     int flags;
     const char* name;
     const char* fmt;
-    int size;
+    int size;     /* Size in bytes */
 } ArmEncodingMap;
 
 /* Keys for target-specific scheduling and other optimization hints */