diff --git a/src/gallium/auxiliary/rtasm/rtasm_ppc_spe.h b/src/gallium/auxiliary/rtasm/rtasm_ppc_spe.h
index 4165a971a2f..61c7edeb604 100644
--- a/src/gallium/auxiliary/rtasm/rtasm_ppc_spe.h
+++ b/src/gallium/auxiliary/rtasm/rtasm_ppc_spe.h
@@ -40,10 +40,10 @@
 /** number of general-purpose SIMD registers */
 #define SPE_NUM_REGS  128
 
-/** Return Address register */
+/** Return Address register (aka $lr / Link Register) */
 #define SPE_REG_RA  0
 
-/** Stack Pointer register */
+/** Stack Pointer register (aka $sp) */
 #define SPE_REG_SP  1