diff --git a/Makefile b/Makefile
index 2db17f8..df69318 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-g -O2 -fPIC -Wall
+CFLAGS=-std=c99 -g -O2 -fPIC -Wall
 LDFLAGS=-g -shared -lpam -lldap
 
 all: pam_csc.so
diff --git a/pam_csc.c b/pam_csc.c
index 69fe1c6..3896e2d 100644
--- a/pam_csc.c
+++ b/pam_csc.c
@@ -7,13 +7,25 @@
 #include <stdlib.h>
 #include <stdbool.h>
 #include <string.h>
-#include <security/pam_modules.h>
 #include <security/pam_appl.h>
+#include <security/pam_modules.h>
 #include <ldap.h>
 #include <sasl/sasl.h>
 #include <syslog.h>
 #include <pwd.h>
 
+#ifndef LDAP_SASL_QUIET
+#  define LDAP_SASL_QUIET 0
+#endif
+
+#ifndef LOG_AUTHPRIV
+#  define LOG_AUTHPRIV LOG_AUTH
+#endif
+
+#ifndef PAM_EXTERN
+#  define PAM_EXTERN extern
+#endif
+
 #define PAM_CSC_CSC_BASE_DN         "ou=People,dc=csclub,dc=uwaterloo,dc=ca"
 #define PAM_CSC_CSCF_URI \
     "ldaps://eponina.student.cs.uwaterloo.ca" \