Index: html.c
===================================================================
--- html.c	(revision 5547)
+++ html.c	(working copy)
@@ -175,7 +175,8 @@
 {
   (void)prompt;
 
-  fprintf(stderr, "DEBUG: cgi_null_passwd(prompt=\"%s\") called!\n", prompt);
+  fprintf(stderr, "DEBUG: cgi_null_passwd(prompt=\"%s\") called!\n",
+          prompt ? prompt : "(null)");
 
   return (NULL);
 }
Index: printers.c
===================================================================
--- printers.c	(revision 5547)
+++ printers.c	(working copy)
@@ -331,7 +331,7 @@
 
 
   fprintf(stderr, "DEBUG: show_all_printers(http=%p, user=\"%s\")\n",
-          http, user);
+          http, user ? user : "(null)");
 
  /*
   * Show the standard header...
@@ -543,7 +543,7 @@
 
 
   fprintf(stderr, "DEBUG: show_printer(http=%p, printer=\"%s\")\n",
-          http, printer);
+          http, printer ? printer : "(null)");
 
  /*
   * Build an IPP_GET_PRINTER_ATTRIBUTES request, which requires the following
Index: template.c
===================================================================
--- template.c	(revision 5547)
+++ template.c	(working copy)
@@ -60,7 +60,7 @@
 
 
   fprintf(stderr, "DEBUG: cgiCopyTemplateFile(out=%p, tmpl=\"%s\")\n", out,
-          tmpl);
+          tmpl ? tmpl : "(null)");
 
  /*
   * Open the template file...
@@ -69,7 +69,7 @@
   if ((in = fopen(tmpl, "r")) == NULL)
   {
     fprintf(stderr, "ERROR: Unable to open template file \"%s\" - %s\n",
-            tmpl, strerror(errno));
+            tmpl ? tmpl : "(null)", strerror(errno));
     return;
   }
 
@@ -102,7 +102,8 @@
   FILE		*in;			/* Input file */
 
 
-  fprintf(stderr, "DEBUG: cgiCopyTemplateLang(tmpl=\"%s\")\n", tmpl);
+  fprintf(stderr, "DEBUG: cgiCopyTemplateLang(tmpl=\"%s\")\n",
+          tmpl ? tmpl : "(null)");
 
  /*
   * Convert the language to a locale name...
Index: ipp-var.c
===================================================================
--- ipp-var.c	(revision 5547)
+++ ipp-var.c	(working copy)
@@ -774,7 +774,7 @@
 
   fprintf(stderr, "DEBUG2: cgiSetIPPObjectVars(obj=%p, prefix=\"%s\", "
                   "element=%d)\n",
-          obj, prefix, element);
+          obj, prefix ? prefix : "(null)", element);
 
  /*
   * Set common CGI template variables...
@@ -977,7 +977,9 @@
 
   fprintf(stderr, "DEBUG2: cgiSetIPPVars(response=%p, filter_name=\"%s\", "
                   "filter_value=\"%s\", prefix=\"%s\", parent_el=%d)\n",
-          response, filter_name, filter_value, prefix, parent_el);
+          response, filter_name ? filter_name : "(null)",
+	  filter_value ? filter_value : "(null)",
+	  prefix ? prefix : "(null)", parent_el);
 
  /*
   * Set common CGI template variables...
Index: help.c
===================================================================
--- help.c	(revision 5547)
+++ help.c	(working copy)
@@ -187,7 +187,8 @@
   topic = cgiGetVariable("TOPIC");
   si    = helpSearchIndex(hi, query, topic, helpfile);
 
-  fprintf(stderr, "DEBUG: query=\"%s\", topic=\"%s\"\n", query, topic);
+  fprintf(stderr, "DEBUG: query=\"%s\", topic=\"%s\"\n",
+          query ? query : "(null)", topic ? topic : "(null)");
 
   if (si)
   {
Index: admin.c
===================================================================
--- admin.c	(revision 5547)
+++ admin.c	(working copy)
@@ -93,7 +93,8 @@
   if (!http)
   {
     perror("ERROR: Unable to connect to cupsd");
-    fprintf(stderr, "DEBUG: cupsServer()=\"%s\"\n", cupsServer());
+    fprintf(stderr, "DEBUG: cupsServer()=\"%s\"\n",
+            cupsServer() ? cupsServer() : "(null)");
     fprintf(stderr, "DEBUG: ippPort()=%d\n", ippPort());
     fprintf(stderr, "DEBUG: cupsEncryption()=%d\n", cupsEncryption());
     exit(1);
@@ -534,8 +535,9 @@
 		};
 
 
+  ptr = cgiGetVariable("DEVICE_URI");
   fprintf(stderr, "DEBUG: do_am_printer: DEVICE_URI=\"%s\"\n",
-          cgiGetVariable("DEVICE_URI"));
+          ptr ? ptr : "(null)");
 
   title = cgiText(modify ? _("Modify Printer") : _("Add Printer"));
 
Index: var.c
===================================================================
--- var.c	(revision 5547)
+++ var.c	(working copy)
@@ -949,7 +949,8 @@
 {
   (void)prompt;
 
-  fprintf(stderr, "DEBUG: cgi_passwd(prompt=\"%s\") called!\n", prompt);
+  fprintf(stderr, "DEBUG: cgi_passwd(prompt=\"%s\") called!\n",
+          prompt ? prompt : "(null)");
 
  /*
   * Send a 401 (unauthorized) status to the server, so it can notify