diff -up pdksh-5.2.14/lex.c.aliases pdksh-5.2.14/lex.c
--- pdksh-5.2.14/lex.c.aliases	2008-12-01 14:29:16.000000000 +0100
+++ pdksh-5.2.14/lex.c	2008-12-03 10:35:42.879559617 +0100
@@ -744,16 +744,25 @@ Done:
 		if ((cf & ALIAS) && (p = tsearch(&aliases, ident, h))
 		    && (p->flag & ISSET))
 		{
-			register Source *s;
+			register Source *s = source;
 
-			for (s = source; s->type == SALIAS; s = s->next)
+			while (s->flags & SF_HASALIAS)
 				if (s->u.tblp == p)
 					return LWORD;
+				else
+					s = s->next;
+
 			/* push alias expansion */
 			s = pushs(SALIAS, source->areap);
 			s->start = s->str = p->val.s;
 			s->u.tblp = p;
+			s->flags |= SF_HASALIAS;
 			s->next = source;
+			if (source->type == SEOF) {
+				/* prevent infinite recursion at EOS */
+				source->u.tblp = p;
+				source->flags |= SF_HASALIAS;
+			}
 			source = s;
 			afree(yylval.cp, ATEMP);
 			goto Again;
diff -up pdksh-5.2.14/lex.h.aliases pdksh-5.2.14/lex.h
--- pdksh-5.2.14/lex.h.aliases	2008-12-03 10:37:42.558592408 +0100
+++ pdksh-5.2.14/lex.h	2008-12-03 10:41:02.040559514 +0100
@@ -14,7 +14,7 @@ struct source {
 	union {
 		char **strv;	/* string [] */
 		struct shf *shf; /* shell file */
-		struct tbl *tblp; /* alias (SALIAS) */
+		struct tbl *tblp; /* alias (SF_HASALIAS) */
 		char *freeme;	/* also for SREREAD */
 	} u;
 	char	ugbuf[2];	/* buffer for ungetsc() (SREREAD) and
@@ -44,6 +44,7 @@ struct source {
 #define SF_ALIAS	BIT(1)	/* faking space at end of alias */
 #define SF_ALIASEND	BIT(2)	/* faking space at end of alias */
 #define SF_TTY		BIT(3)	/* type == SSTDIN & it is a tty */
+#define SF_HASALIAS	BIT(5)	/* u.tblp valid (SALIAS, SEOF) */
 
 /*
  * states while lexing word