diff --git a/includes/discovery/os/ibm-amm.inc.php b/includes/discovery/os/ibm-amm.inc.php
index 6909fe59c4..0e796cc805 100644
--- a/includes/discovery/os/ibm-amm.inc.php
+++ b/includes/discovery/os/ibm-amm.inc.php
@@ -10,8 +10,6 @@
  * the source code distribution for details.
  */
 
-if (!$os) {
-    if (stristr($sysDescr, 'BladeCenter Advanced Management Module')) {
-        $os = 'ibm-amm';
-    }
+if (str_contains($sysDescr, 'BladeCenter Advanced Management Module')) {
+    $os = 'ibm-amm';
 }
diff --git a/includes/discovery/os/ibm-imm.inc.php b/includes/discovery/os/ibm-imm.inc.php
index 22874412ab..7a4bdff599 100644
--- a/includes/discovery/os/ibm-imm.inc.php
+++ b/includes/discovery/os/ibm-imm.inc.php
@@ -10,8 +10,6 @@
  * the source code distribution for details.
  */
 
-if (!$os) {
-    if (strstr($sysObjectId, '1.3.6.1.4.1.2.3.51.3')) {
-        $os = 'ibm-imm';
-    }
+if (starts_with($sysObjectId, '1.3.6.1.4.1.2.3.51.3')) {
+    $os = 'ibm-imm';
 }
diff --git a/includes/discovery/os/ibmnos.inc.php b/includes/discovery/os/ibmnos.inc.php
index 9f72ae692b..a6186914a0 100644
--- a/includes/discovery/os/ibmnos.inc.php
+++ b/includes/discovery/os/ibmnos.inc.php
@@ -10,8 +10,6 @@
  * the source code distribution for details.
  */
 
-if (!$os) {
-    if (stristr($sysDescr, 'IBM Networking Operating System') || stristr($sysDescr, 'IBM Flex System Fabric') || stristr($sysDescr, 'IBM Networking OS')) {
-        $os = 'ibmnos';
-    }
+if (str_contains($sysDescr, array('IBM Networking Operating System', 'IBM Flex System Fabric', 'IBM Networking OS'))) {
+    $os = 'ibmnos';
 }
diff --git a/includes/discovery/os/ibmtl.inc.php b/includes/discovery/os/ibmtl.inc.php
index 4c53b776b5..57e6d37689 100644
--- a/includes/discovery/os/ibmtl.inc.php
+++ b/includes/discovery/os/ibmtl.inc.php
@@ -10,9 +10,8 @@
 * the source code distribution for details.
 */
 
-if (!$os) {
-    $ibmtl_snmpget = snmp_get($device, 'SML-MIB::product-Name.0', '-Oqv', '');
-    if (stristr($ibmtl_snmpget, 'IBM System Storage TS3500 Tape Library')) {
-        $os = 'ibmtl';
-    }
+$ibmtl_snmpget = snmp_get($device, 'SML-MIB::product-Name.0', '-Oqv', '');
+
+if (str_contains($ibmtl_snmpget, 'IBM System Storage TS3500 Tape Library')) {
+    $os = 'ibmtl';
 }
diff --git a/includes/discovery/os/ies.inc.php b/includes/discovery/os/ies.inc.php
index 1079ba8d8f..d8787dd34e 100644
--- a/includes/discovery/os/ies.inc.php
+++ b/includes/discovery/os/ies.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (!$os) {
-    if (strstr($sysDescr, 'IES-') && !strstr($sysDescr, 'Cisco Systems')) {
-        $os = 'ies';
-    }
+if (str_contains($sysDescr, 'IES-') && !str_contains($sysDescr, 'Cisco Systems')) {
+    $os = 'ies';
 }
diff --git a/includes/discovery/os/infinity.inc.php b/includes/discovery/os/infinity.inc.php
index 517cdfaf3e..f4e20caa26 100644
--- a/includes/discovery/os/infinity.inc.php
+++ b/includes/discovery/os/infinity.inc.php
@@ -10,8 +10,6 @@
  * the source code distribution for details.
  */
 
-if (!$os) {
-    if (preg_match('/^NFT 2N/', $sysDescr)) {
-        $os = 'infinity';
-    }
+if (starts_with($sysDescr, 'NFT 2N')) {
+    $os = 'infinity';
 }
diff --git a/includes/discovery/os/ios.inc.php b/includes/discovery/os/ios.inc.php
index caedad1d9f..23c82d0207 100644
--- a/includes/discovery/os/ios.inc.php
+++ b/includes/discovery/os/ios.inc.php
@@ -1,32 +1,20 @@
 <?php
 
-if (empty($os)) {
-    if (strstr($sysDescr, 'Cisco Internetwork Operating System Software')) {
-        $os = 'ios';
-    } elseif (strstr($sysDescr, 'IOS (tm)')) {
-        $os = 'ios';
-    } elseif (strstr($sysDescr, 'Cisco IOS Software')) {
-        $os = 'ios';
-    } elseif (strstr($sysDescr, 'Global Site Selector')) {
-        $os = 'ios';
-    }
-
-    if (strstr($sysDescr, 'IOS-XE')) {
-        $os = 'iosxe';
-    }
-
-    if (strstr($sysDescr, 'IOS XR')) {
-        $os = 'iosxr';
-    }
-
-    if (!empty($os)) {
-        $extra_mibs = array(
-            "ciscoAAASessionMIB" => "CISCO-AAA-SESSION-MIB",
-        );
-        register_mibs($device, $extra_mibs, "includes/discovery/os/ios.inc.php");
-    }
+if (str_contains($sysDescr, array('Cisco Internetwork Operating System Software', 'IOS (tm)', 'Cisco IOS Software', 'Global Site Selector'))) {
+    $os = 'ios';
 }
 
-// Fallback case
-// If we don't have an OS yet and if the object is in Cisco tree it's most likely an IOS device
-// if (empty($os) and substr($sysObjectId, 0, 17) == ".1.3.6.1.4.1.9.1.") { $os = "ios"; }
+if (str_contains($sysDescr, 'IOS-XE')) {
+    $os = 'iosxe';
+}
+
+if (str_contains($sysDescr, 'IOS XR')) {
+    $os = 'iosxr';
+}
+
+if (!empty($os)) {
+    $extra_mibs = array(
+        "ciscoAAASessionMIB" => "CISCO-AAA-SESSION-MIB",
+    );
+    register_mibs($device, $extra_mibs, "includes/discovery/os/ios.inc.php");
+}
diff --git a/includes/discovery/os/ipoman.inc.php b/includes/discovery/os/ipoman.inc.php
index 97c753b911..113f2f17f6 100644
--- a/includes/discovery/os/ipoman.inc.php
+++ b/includes/discovery/os/ipoman.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (!$os) {
-    if (strstr($sysObjectId, '1.3.6.1.4.1.2468.1.4.2.1')) {
-        $os = 'ipoman';
-    }
+if (starts_with($sysObjectId, '.1.3.6.1.4.1.2468.1.4.2.1')) {
+    $os = 'ipoman';
 }
diff --git a/includes/discovery/os/ironware.inc.php b/includes/discovery/os/ironware.inc.php
index 110f6b039f..61c519b612 100644
--- a/includes/discovery/os/ironware.inc.php
+++ b/includes/discovery/os/ironware.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (!$os) {
-    if (preg_match('/IronWare/', $sysDescr)) {
-        $os = 'ironware';
-    }
+if (str_contains($sysDescr, 'IronWare')) {
+    $os = 'ironware';
 }
diff --git a/includes/discovery/os/ise.inc.php b/includes/discovery/os/ise.inc.php
index ea22af8d2d..75cb879de0 100644
--- a/includes/discovery/os/ise.inc.php
+++ b/includes/discovery/os/ise.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (!$os) {
-    if ((strstr($sysObjectId, '.1.3.6.1.4.1.9.1.2139')) || (strstr($sysObjectId, '.1.3.6.1.4.1.9.1.1426'))) {
-        $os = 'ise';
-    }
+if (starts_with($sysObjectId, array('.1.3.6.1.4.1.9.1.2139', '.1.3.6.1.4.1.9.1.1426'))) {
+    $os = 'ise';
 }