diff -Naur a/backend/src/cnij_backend_common.c b/backend/src/cnij_backend_common.c
--- a/backend/src/cnij_backend_common.c	2010-02-23 04:57:49.000000000 +0100
+++ b/backend/src/cnij_backend_common.c	2011-11-17 12:59:27.482025762 +0100
@@ -38,6 +38,7 @@
 // CUPS Header
 #include <cups/cups.h>
 #include <cups/ipp.h>
+#include <cups/ppd.h>
 
 // Header file for CANON
 #include "cnij_backend_common.h"

--- a/cngpijmon/src/bjcupsmon_cups.c	2012-03-17 12:32:43.230805896 +0100
+++ b/cngpijmon/src/bjcupsmon_cups.c	2012-03-17 12:34:23.179018171 +0100
@@ -18,8 +18,10 @@
 */
 
 /*** Includes ***/
+#define _IPP_PRIVATE_STRUCTURES 1
 #include <cups/cups.h>
 #include <cups/language.h>
+#include <cups/ppd.h>
 #include <sys/types.h>
 #include <unistd.h>

--- a/cngpij/cngpij/bjcups.c	2012-07-31 05:22:51.613991808 -0400
+++ b/cngpij/cngpij/bjcups.c	 2012-07-31 05:23:14.780658321 -0400
@@ -21,6 +21,7 @@
 #include	<config.h>
 #endif	// HAVE_CONFIG_H
 
+#define _IPP_PRIVATE_STRUCTURES 1
 #include <cups/cups.h>
 #include <cups/language.h>
 #include <cups/ppd.h>
diff -Naur a/cngpij/cngpij/bjcups.c b/cngpij/cngpij/bjcups.c
--- a/cngpij/cngpij/bjcups.c	2019-10-31 15:00:19.000000000 +0200
+++ b/cngpij/cngpij/bjcups.c	2019-10-31 15:14:44.505666529 +0200
@@ -66,6 +66,48 @@
 extern int GetIPCData(LPIPCU pipc, char *sname);
 
 
+#if (CUPS_VERSION_MAJOR > 1) || (CUPS_VERSION_MINOR > 5)
+#define HAVE_CUPS_1_6 1
+#endif
+
+#ifndef HAVE_CUPS_1_6
+#define ippGetCount(attr)     attr->num_values
+#define ippGetGroupTag(attr)  attr->group_tag
+#define ippGetValueTag(attr)  attr->value_tag
+#define ippGetName(attr)      attr->name
+#define ippGetBoolean(attr, element) attr->values[element].boolean
+#define ippGetInteger(attr, element) attr->values[element].integer
+#define ippGetStatusCode(ipp) ipp->request.status.status_code
+#define ippGetString(attr, element, language) attr->values[element].string.text
+
+static ipp_attribute_t * ippFirstAttribute( ipp_t *ipp )
+{
+	if (!ipp)
+		return (NULL);
+	return (ipp->current = ipp->attrs);
+}
+
+static ipp_attribute_t * ippNextAttribute( ipp_t *ipp )
+{
+	if (!ipp || !ipp->current)
+		return (NULL);
+	return (ipp->current = ipp->current->next);
+}
+
+static int ippSetOperation( ipp_t *ipp, ipp_op_t op )
+{
+	ipp->request.op.operation_id = op;
+	return (1);
+}
+
+static int ippSetRequestId( ipp_t *ipp, int request_id )
+{
+	ipp->request.any.request_id = request_id;
+	return (1);
+}
+#endif
+
+
 int get_value_and_param_array(short id, short** value, char*** param)
 {
 	int count;
@@ -689,8 +731,8 @@
 	else {
 		pRequest = ippNew();
 		
-		pRequest->request.op.operation_id = CUPS_GET_PRINTERS;
-		pRequest->request.op.request_id   = 1;
+		ippSetOperation(pRequest, CUPS_GET_PRINTERS);
+		ippSetRequestId(pRequest, 1);
 		
 		pLanguage = bjcupsLangDefault();	// cupsLangDefault() -> bjcupsLangDefault() for cups-1.1.19
 		
@@ -699,29 +741,29 @@
 		ippAddString(pRequest, IPP_TAG_OPERATION, IPP_TAG_URI, "printer-uri", NULL, NULL);
 		
 		if ((pResponse = cupsDoRequest(pHTTP, pRequest, "/")) != NULL) {
-			if (pResponse->request.status.status_code > IPP_OK_CONFLICT) {
+			if (ippGetStatusCode(pResponse) > IPP_OK_CONFLICT) {
 				fputs("ERROR: IPP ERROR\n", stderr);
 				goto onErr;
 			}
 			else {
-				pAttribute = pResponse->attrs;
+				pAttribute = ippFirstAttribute(pResponse);
 
 				while (pAttribute != NULL) {
-					while (pAttribute != NULL && pAttribute->group_tag != IPP_TAG_PRINTER) {
-						pAttribute = pAttribute->next;
+					while (pAttribute != NULL && ippGetGroupTag(pAttribute) != IPP_TAG_PRINTER) {
+						pAttribute = ippNextAttribute(pAttribute);
 					}
 					if (pAttribute == NULL) {
 						break;
 					}
 					
-					while (pAttribute != NULL && pAttribute->group_tag == IPP_TAG_PRINTER) {
-						if (strcmp(pAttribute->name, "printer-name") == 0 && pAttribute->value_tag == IPP_TAG_NAME) {
-							pPrinter = pAttribute->values[0].string.text;
+					while (pAttribute != NULL && ippGetGroupTag(pAttribute) == IPP_TAG_PRINTER) {
+						if (strcmp(ippGetName(pAttribute), "printer-name") == 0 && ippGetValueTag(pAttribute) == IPP_TAG_NAME) {
+							pPrinter = ippGetString(pAttribute, 0, "");
 						}
-						if (strcmp(pAttribute->name, "device-uri") == 0 && pAttribute->value_tag == IPP_TAG_URI) {
-							pDUri = pAttribute->values[0].string.text;
+						if (strcmp(ippGetName(pAttribute), "device-uri") == 0 && ippGetValueTag(pAttribute) == IPP_TAG_URI) {
+							pDUri = ippGetString(pAttribute, 0, "");
 						}
-						pAttribute = pAttribute->next;
+						pAttribute = ippNextAttribute(pAttribute);
 					}
 
 					if (strcasecmp(pDestName, pPrinter) == 0) {
@@ -730,7 +772,7 @@
 					}
 					
 					if (pAttribute != NULL)
-						 pAttribute = pAttribute->next;
+						 pAttribute = ippNextAttribute(pAttribute);
 				}
 			}