diff --git a/includes/discovery/os/procurve.inc.php b/includes/discovery/os/procurve.inc.php
index 651b4a6b65..1c484495ed 100644
--- a/includes/discovery/os/procurve.inc.php
+++ b/includes/discovery/os/procurve.inc.php
@@ -1,5 +1,9 @@
 <?php
 
+if (str_contains($sysDescr, array('ProCurve', 'HP 1820'))) {
+    $os = 'procurve';
+}
+
 if (!$os) {
     if (stristr($sysDescr, 'ProCurve') || stristr($sysDescr, 'HP 1820')) {
         $os = 'procurve';
diff --git a/includes/discovery/os/proxim.inc.php b/includes/discovery/os/proxim.inc.php
index 84de7548de..fb9386c154 100644
--- a/includes/discovery/os/proxim.inc.php
+++ b/includes/discovery/os/proxim.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (!$os) {
-    if (strstr($sysObjectId, '.1.3.6.1.4.1.11898.2.4.9')) {
-        $os = 'proxim';
-    }
+if (starts_with($sysObjectId, '.1.3.6.1.4.1.11898.2.4.9')) {
+    $os = 'proxim';
 }
diff --git a/includes/discovery/os/pulse.inc.php b/includes/discovery/os/pulse.inc.php
index 608403dc03..4a5291a7f0 100644
--- a/includes/discovery/os/pulse.inc.php
+++ b/includes/discovery/os/pulse.inc.php
@@ -9,8 +9,7 @@
  * option) any later version.  Please see LICENSE.txt at the top level of
  * the source code distribution for details.
  */
-if (!$os) {
-    if (strstr($sysDescr, 'Pulse Connect Secure')) {
-        $os = 'pulse';
-    }
+
+if (str_contains($sysDescr, 'Pulse Connect Secure')) {
+    $os = 'pulse';
 }
diff --git a/includes/discovery/os/quanta.inc.php b/includes/discovery/os/quanta.inc.php
index ee765aa95f..e1107eb162 100644
--- a/includes/discovery/os/quanta.inc.php
+++ b/includes/discovery/os/quanta.inc.php
@@ -1,6 +1,9 @@
 <?php
-if (!$os) {
-    if (strstr($sysObjectId, '.1.3.6.1.4.1.4413') || strstr($sysObjectId, '.1.3.6.1.4.1.7244') && (stristr($sysDescr, 'vxworks') || stristr($sysDescr, 'Quanta'))) {
-        $os = 'quanta';
-    }
+
+if (starts_with($sysObjectId, array('.1.3.6.1.4.1.4413', '.1.3.6.1.4.1.7244'))) {
+    $os = 'quanta';
+}
+
+if (str_contains($sysDescr, array('vxworks', 'Quanta'))) {
+    $os = 'quanta';
 }
diff --git a/includes/discovery/os/radlan.inc.php b/includes/discovery/os/radlan.inc.php
index 1474289736..326861f2a3 100644
--- a/includes/discovery/os/radlan.inc.php
+++ b/includes/discovery/os/radlan.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (!$os) {
-    if (strstr($sysDescr, 'AT-8000')) {
-        $os = 'radlan';
-    }           //end if
+if (str_contains($sysDescr, 'AT-8000')) {
+    $os = 'radlan';
 }
diff --git a/includes/discovery/os/raisecom.inc.php b/includes/discovery/os/raisecom.inc.php
index 7c6b6170ec..012265e09b 100644
--- a/includes/discovery/os/raisecom.inc.php
+++ b/includes/discovery/os/raisecom.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (!$os) {
-    if (strstr($sysObjectId, '.1.3.6.1.4.1.8886')) {
-        $os = 'raisecom';
-    }
+if (starts_with($sysObjectId, '.1.3.6.1.4.1.8886')) {
+    $os = 'raisecom';
 }
diff --git a/includes/discovery/os/raritan.inc.php b/includes/discovery/os/raritan.inc.php
index 15fa15803c..1150f29891 100644
--- a/includes/discovery/os/raritan.inc.php
+++ b/includes/discovery/os/raritan.inc.php
@@ -1,19 +1,5 @@
 <?php
 
-if (!$os) {
-    if (strstr($sysDescr, 'Raritan')) {
-        $os = 'raritan';
-    }
-}
-
-if (!$os) {
-    if (strstr($sysDescr, 'PX2')) {
-        $os = 'raritan';
-    }
-}
-
-if (!$os) {
-    if (strstr($sysDescr, 'Raritan')) {
-        $os = 'raritan';
-    }
+if (str_contains($sysDescr, array('Raritan', 'PX2'))) {
+    $os = 'raritan';
 }
diff --git a/includes/discovery/os/redback.inc.php b/includes/discovery/os/redback.inc.php
index 4905b1f3dd..8a40f40560 100644
--- a/includes/discovery/os/redback.inc.php
+++ b/includes/discovery/os/redback.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (!$os) {
-    if (preg_match('/Redback/', $sysDescr)) {
-        $os = 'redback';
-    }
+if (str_contains($sysDescr, 'Redback')) {
+    $os = 'redback';
 }
diff --git a/includes/discovery/os/ricoh.inc.php b/includes/discovery/os/ricoh.inc.php
index 2079e74540..921eeac334 100644
--- a/includes/discovery/os/ricoh.inc.php
+++ b/includes/discovery/os/ricoh.inc.php
@@ -1,11 +1,5 @@
 <?php
 
-if (!$os) {
-    if (strstr($sysDescr, 'RICOH Aficio')) {
-        $os = 'ricoh';
-    }
-
-    if (stristr($sysDescr, 'RICOH Network Printer')) {
-        $os = 'ricoh';
-    }
+if (str_contains($sysDescr, array('RICOH Aficio', 'RICOH Network Printer'))) {
+    $os = 'ricoh';
 }
diff --git a/includes/discovery/os/riverbed.inc.php b/includes/discovery/os/riverbed.inc.php
index f97e68fd82..755cf86b29 100644
--- a/includes/discovery/os/riverbed.inc.php
+++ b/includes/discovery/os/riverbed.inc.php
@@ -9,8 +9,7 @@
  * option) any later version.  Please see LICENSE.txt at the top level of
  * the source code distribution for details.
  */
-if (!$os) {
-    if (strpos($sysObjectId, '1.3.6.1.4.1.17163.1.1') !== false) {
-        $os = 'riverbed';
-    }
+
+if (starts_with($sysObjectId, '1.3.6.1.4.1.17163.1.1')) {
+    $os = 'riverbed';
 }
diff --git a/includes/discovery/os/routeros.inc.php b/includes/discovery/os/routeros.inc.php
index 1918c9cd19..1622839043 100644
--- a/includes/discovery/os/routeros.inc.php
+++ b/includes/discovery/os/routeros.inc.php
@@ -1,25 +1,16 @@
 <?php
 
-if (!$os) {
-    // RouterOS <= 4
-    // sysDescr.0 = STRING: router
-    if ($sysDescr == 'router') {
-        if (is_numeric(snmp_get($device, 'SNMPv2-SMI::enterprises.14988.1.1.4.3.0', '-Oqv', ''))) {
-            $os = 'routeros';
-        }
-    }
-
-    // Routeros >= 5
-    // sysDescr.0 = STRING: RouterOS RB493AH
-    if (preg_match('/^RouterOS/', $sysDescr)) {
-        $os = 'routeros';
-    }
-
-    // poll Cisco AAA MIB
-    if (!empty($os)) {
-        $extra_mibs = array(
-            "ciscoAAASessionMIB" => "CISCO-AAA-SESSION-MIB",
-        );
-        register_mibs($device, $extra_mibs, "includes/discovery/os/routeros.inc.php");
-    }
+if (str_contains($sysDescr, 'router') && is_numeric(snmp_get($device, 'SNMPv2-SMI::enterprises.14988.1.1.4.3.0', '-Oqv', ''))) {
+    $os = 'routeros';
+}
+
+if (str_contains($sysDescr, 'RouterOS')) {
+    $os = 'routeros';
+}
+
+if (!empty($os)) {
+    $extra_mibs = array(
+        "ciscoAAASessionMIB" => "CISCO-AAA-SESSION-MIB",
+    );
+    register_mibs($device, $extra_mibs, "includes/discovery/os/routeros.inc.php");
 }
diff --git a/includes/discovery/os/ruckuswireless.inc.php b/includes/discovery/os/ruckuswireless.inc.php
index dad1284847..5790ccd8f8 100644
--- a/includes/discovery/os/ruckuswireless.inc.php
+++ b/includes/discovery/os/ruckuswireless.inc.php
@@ -12,16 +12,14 @@
  * the source code distribution for details.
  */
 
-if (!$os) {
-    if (strstr($sysObjectId, '.1.3.6.1.4.1.25053.3.1')) {
-        $os = 'ruckuswireless';
+if (starts_with($sysObjectId, '.1.3.6.1.4.1.25053.3.1')) {
+    $os = 'ruckuswireless';
 
-        $ruckus_mibs = array(
-            "ruckusZDSystemStats"           => "RUCKUS-ZD-SYSTEM-MIB",
-            "ruckusZDWLANTable"             => "RUCKUS-ZD-WLAN-MIB",
-            "ruckusZDWLANAPTable"           => "RUCKUS-ZD-WLAN-MIB",
-            "ruckusZDWLANAPRadioStatsTable" => "RUCKUS-ZD-WLAN-MIB",
-        );
-        register_mibs($device, $ruckus_mibs, "includes/discovery/os/ruckuswireless.inc.php");
-    }
+    $ruckus_mibs = array(
+        "ruckusZDSystemStats"           => "RUCKUS-ZD-SYSTEM-MIB",
+        "ruckusZDWLANTable"             => "RUCKUS-ZD-WLAN-MIB",
+        "ruckusZDWLANAPTable"           => "RUCKUS-ZD-WLAN-MIB",
+        "ruckusZDWLANAPRadioStatsTable" => "RUCKUS-ZD-WLAN-MIB",
+    );
+    register_mibs($device, $ruckus_mibs, "includes/discovery/os/ruckuswireless.inc.php");
 }