diff --git a/ajax.php b/ajax.php
index ddf87d6..c7b47fa 100644
--- a/ajax.php
+++ b/ajax.php
@@ -32,7 +32,7 @@ if ($_GET['section'] == "localTx") {
             $listElem[3] = getName($listElem[2]);
             if ($listElem[2] !== "??????????") {
                if (!is_numeric($listElem[2])) {
-                  if (constant("SHOWQRZ")) {
+                  if (defined("SHOWQRZ")) {
                      $listElem[2] = "<a target=\"_new\" href=\"https://qrz.com/db/$listElem[2]\">".str_replace("0","&Oslash;",$listElem[2])."</a>";
                   } else {
                      $listElem[2] = "<a target=\"_new\" href=\"http://dmr.darc.de/dmr-userreg.php?callsign=$listElem[2]\">".$listElem[2]."</a>";
@@ -47,7 +47,7 @@ if ($_GET['section'] == "localTx") {
          if ($listElem[5] == "RF" && ($listElem[1]=="D-Star" || startsWith($listElem[1], "DMR") || $listElem[1]=="YSF" || $listElem[1]=="P25")) {
             if ($listElem[2] !== "??????????") {
                if (!is_numeric($listElem[2])) {
-                  if (constant("SHOWQRZ")) {
+                  if (defined("SHOWQRZ")) {
                      $listElem[2] = "<a target=\"_new\" href=\"https://qrz.com/db/$listElem[2]\">".str_replace("0","&Oslash;",$listElem[2])."</a>";
                   } else {
                      $listElem[2] = "<a target=\"_new\" href=\"http://dmr.darc.de/dmr-userreg.php?callsign=$listElem[2]\">".$listElem[2]."</a>";
diff --git a/include/functions.php b/include/functions.php
index 0905381..2be0e12 100644
--- a/include/functions.php
+++ b/include/functions.php
@@ -436,7 +436,7 @@ function getLastHeard($logLines, $onlyLast) {
             }
             if ($listElem[2] !== "??????????") {
                if (!is_numeric($listElem[2])) {
-                  if (constant("SHOWQRZ")) {
+                  if (defined("SHOWQRZ")) {
                      $listElem[2] = "<a target=\"_new\" href=\"https://qrz.com/db/$listElem[2]\">".str_replace("0","&Oslash;",$listElem[2])."</a>";
                   } else {
                      $listElem[2] = "<a target=\"_new\" href=\"http://dmr.darc.de/dmr-userreg.php?callsign=$listElem[2]\">".$listElem[2]."</a>";
diff --git a/include/lh.php b/include/lh.php
index 6e50b4c..1574dee 100644
--- a/include/lh.php
+++ b/include/lh.php
@@ -36,7 +36,7 @@ for ($i = 0;  ($i < $totalLH); $i++) {
       echo"<td nowrap>$listElem[1]</td>";
       if ($listElem[2] !== "??????????") {
          if (!is_numeric($listElem[2])) {
-            if (constant("SHOWQRZ")) {
+            if (defined("SHOWQRZ")) {
                echo"<td nowrap><a target=\"_new\" href=\"https://qrz.com/db/$listElem[2]\">".str_replace("0","&Oslash;",$listElem[2])."</a></td>";
             } else {
                echo"<td nowrap><a target=\"_new\" href=\"http://dmr.darc.de/dmr-userreg.php?callsign=$listElem[2]\">".$listElem[2]."</td>";
diff --git a/include/localtx.php b/include/localtx.php
index 3913dd6..16e8aa2 100644
--- a/include/localtx.php
+++ b/include/localtx.php
@@ -41,7 +41,7 @@ for ($i = 0; $i < count($localTXList); $i++) {
       echo"<td nowrap>$listElem[1]</td>";
       if ($listElem[2] !== "??????????") {
          if (!is_numeric($listElem[2])) {
-            if (constant("SHOWQRZ")) {
+            if (defined("SHOWQRZ")) {
                echo"<td nowrap><a target=\"_new\" href=\"https://qrz.com/db/$listElem[2]\">".str_replace("0","&Oslash;",$listElem[2])."</a></td>";
             } else {
                echo"<td nowrap><a target=\"_new\" href=\"http://dmr.darc.de/dmr-userreg.php?callsign=$listElem[2]\">".$listElem[2]."</td>";
diff --git a/txinfo.php b/txinfo.php
index 372cde6..290ff00 100644
--- a/txinfo.php
+++ b/txinfo.php
@@ -27,7 +27,7 @@ foreach ($lastHeard as $listElem) {
       echo"<td nowrap>$listElem[1]</td>";
       /*if ($listElem[2] !== "??????????") {
          if (!is_numeric($listElem[2])) {
-            if (constant("SHOWQRZ")) {
+            if (defined("SHOWQRZ")) {
                echo"<td nowrap><a target=\"_new\" href=\"https://qrz.com/db/$listElem[2]\">".str_replace("0","&Oslash;",$listElem[2])."</a></td>";
             } else {
                echo"<td nowrap><a target=\"_new\" href=\"http://dmr.darc.de/dmr-userreg.php?callsign=$listElem[2]\">".$listElem[2]."</td>";