diff -uNrp -x '*~' coreutils-5.97-orig/src/su.c coreutils-5.97/src/su.c
--- coreutils-5.97-orig/src/su.c	2006-07-13 12:14:40.000000000 +0100
+++ coreutils-5.97/src/su.c	2006-07-13 12:24:33.000000000 +0100
@@ -131,11 +131,15 @@
 
 #include "error.h"
 
-/* The official name of this program (e.g., no `g' prefix).  */
+/* The official name of this program (e.g., no `g' prefix).
+ * - Add a "-l" to the name passed to PAM if this is a login simulation
+ */
 #ifndef RUNUSER
 #define PROGRAM_NAME "su"
+#define PROGRAM_NAME_L "su-l"
 #else
 #define PROGRAM_NAME "runuser"
+#define PROGRAM_NAME_L "runuser-l"
 #endif
 
 #ifndef AUTHORS
@@ -310,7 +314,8 @@ correct_password (const struct passwd *p
 #ifdef USE_PAM
   struct passwd *caller;
   char *tty_name, *ttyn;
-  retval = pam_start(PROGRAM_NAME, pw->pw_name, &conv, &pamh);
+  retval = pam_start(simulate_login ? PROGRAM_NAME_L : PROGRAM_NAME,
+		     pw->pw_name, &conv, &pamh);
   PAM_BAIL_P;
 
 #ifndef RUNUSER