diff --git a/include/vki/vki-ppc32-aix5.h b/include/vki/vki-ppc32-aix5.h
index a3832d398..0780d2761 100644
--- a/include/vki/vki-ppc32-aix5.h
+++ b/include/vki/vki-ppc32-aix5.h
@@ -278,8 +278,7 @@ struct vki_sigaction {
 
 #define VKI_MINSIGSTKSZ 1168
 
-#define VKI_SI_TKILL 0 /* AIX doesn't have this */
-#define VKI_SI_USER  0 /* but it does have this */
+#define VKI_SI_USER  0
 
 #define VKI_SIG_BLOCK      0
 #define VKI_SIG_SETMASK    2
diff --git a/include/vki/vki-ppc64-aix5.h b/include/vki/vki-ppc64-aix5.h
index ebc0a296c..0e3e73fbb 100644
--- a/include/vki/vki-ppc64-aix5.h
+++ b/include/vki/vki-ppc64-aix5.h
@@ -280,8 +280,7 @@ struct vki_sigaction {
 
 #define VKI_MINSIGSTKSZ 1200
 
-#define VKI_SI_TKILL 0 /* AIX doesn't have this */
-#define VKI_SI_USER  0 /* but it does have this */
+#define VKI_SI_USER  0
 
 #define VKI_SIG_BLOCK      0
 #define VKI_SIG_SETMASK    2