diff --git a/src/Makefile b/src/Makefile
index f1d95b1..06e35b5 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,4 +1,4 @@
-CFLAGS = -Wall
+CFLAGS = -Wall -Werror
 TARGETS = in.tokend pointscli claim.cgi puzzler.cgi puzzles.cgi
 
 all: build
diff --git a/src/claim.cgi.c b/src/claim.cgi.c
index ea767ff..d684da3 100644
--- a/src/claim.cgi.c
+++ b/src/claim.cgi.c
@@ -1,4 +1,5 @@
 #include <stdlib.h>
+#include <ctype.h>
 #include "common.h"
 
 int
diff --git a/src/common.c b/src/common.c
index ca7afe0..878c447 100644
--- a/src/common.c
+++ b/src/common.c
@@ -5,6 +5,7 @@
 #include <stdarg.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
 #include <ctype.h>
 #include <values.h>
 #include <time.h>
@@ -357,7 +358,6 @@ award_points(char const *teamhash,
   int    linelen;
   char   *filename;
   int    fd;
-  int    ret;
   time_t now = time(NULL);
 
   if (! team_exists(teamhash)) {
@@ -365,8 +365,8 @@ award_points(char const *teamhash,
   }
 
   linelen = snprintf(line, sizeof(line),
-                     "%u %s %s %ld\n",
-                     now, teamhash, category, points);
+                     "%lu %s %s %ld\n",
+                     (unsigned long)now, teamhash, category, points);
   if (sizeof(line) <= linelen) {
     return -1;
   }
@@ -428,7 +428,6 @@ award_and_log_uniquely(char const *team,
                        char const *line)
 {
   char    *dbpath = srv_path(dbfile);
-  int      ret;
   int      fd;
 
   /* Make sure they haven't already claimed these points */
diff --git a/src/common.h b/src/common.h
index b5b4139..8488271 100644
--- a/src/common.h
+++ b/src/common.h
@@ -16,6 +16,7 @@ void cgi_error(char *fmt, ...);
 
 
 int fgrepx(char const *needle, char const *filename);
+int my_snprintf(char *buf, size_t buflen, char *fmt, ...);
 char *srv_path(char const *fmt, ...);
 int team_exists(char const *teamhash);
 int award_points(char const *teamhacsh,
diff --git a/src/in.tokend.c b/src/in.tokend.c
index c043b78..2850610 100644
--- a/src/in.tokend.c
+++ b/src/in.tokend.c
@@ -7,6 +7,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <stddef.h>
+#include <string.h>
 #include <ctype.h>
 #include "common.h"
 #include "xxtea.h"
@@ -117,7 +118,7 @@ main(int argc, char *argv[])
     for (i = 0; i < itokenlen; i += 1) {
       crap[i] = (uint8_t)random();
     }
-    bubblebabble(digest, crap, itokenlen);
+    bubblebabble(digest, (char *)crap, itokenlen);
 
     /* Append digest to service name. */
     tokenlen = (size_t)my_snprintf(token, sizeof(token),
diff --git a/src/puzzler.cgi.c b/src/puzzler.cgi.c
index 3886a7d..235a110 100644
--- a/src/puzzler.cgi.c
+++ b/src/puzzler.cgi.c
@@ -1,4 +1,5 @@
 #include <stdlib.h>
+#include <ctype.h>
 #include "common.h"
 
 int