diff --git a/src/stub/src/arch/mips/r3000/macros.ash b/src/stub/src/arch/mips/r3000/macros.ash
index 4a17db79..de93edf2 100644
--- a/src/stub/src/arch/mips/r3000/macros.ash
+++ b/src/stub/src/arch/mips/r3000/macros.ash
@@ -35,7 +35,10 @@
         .align  0
 .endm
 
-/* http://math-atlas.sourceforge.net/devel/assembly/mipsabi32.pdf  */
+/* http://math-atlas.sourceforge.net/devel/assembly/mipsabi32.pdf
+ *   When calling position independent functions $25 must contain
+ *   the address of the called function.  [$25 === $t9 === $jp]
+ */
 #define zero    $0
 #define at      $1
 #define v0      $2