diff -ubr popa3d-1.0.2-orig/Makefile popa3d-1.0.2/Makefile
--- popa3d-1.0.2-orig/Makefile	2012-09-19 01:19:56.698098130 +0200
+++ popa3d-1.0.2/Makefile	2012-09-19 01:24:33.871750473 +0200
@@ -9,7 +9,7 @@
 LDFLAGS = -s
 LIBS =
 # Linux with glibc, FreeBSD, NetBSD
-#LIBS += -lcrypt
+LIBS += -lcrypt
 # HP-UX trusted system
 #LIBS += -lsec
 # Solaris (POP_STANDALONE, POP_VIRTUAL)
diff -ubr popa3d-1.0.2-orig/auth_shadow.c popa3d-1.0.2/auth_shadow.c
--- a/auth_shadow.c
+++ b/auth_shadow.c
@@ -14,8 +14,9 @@
 #define _XOPEN_SOURCE 4
 #define _XOPEN_SOURCE_EXTENDED
 #define _XOPEN_VERSION 4
 #define _XPG4_2
+#define _DEFAULT_SOURCE
 #include <unistd.h>
 #include <string.h>
 #include <stdlib.h>
 #include <pwd.h>