diff --git a/application/loginwebpage.class.inc.php b/application/loginwebpage.class.inc.php
index 33827e493..a7ecd12fb 100644
--- a/application/loginwebpage.class.inc.php
+++ b/application/loginwebpage.class.inc.php
@@ -910,13 +910,13 @@ class LoginWebPage extends NiceWebPage
 			$aAllProfiles = array();
 			while ($oProfile = $oProfilesSet->Fetch())
 			{
-				$aAllProfiles[strtolower($oProfile->GetName())] = $oProfile->GetKey();
+				$aAllProfiles[mb_strtolower($oProfile->GetName())] = $oProfile->GetKey();
 			}
 
 			$aProfiles = array();
 			foreach ($aRequestedProfiles as $sRequestedProfile)
 			{
-				$sRequestedProfile = strtolower($sRequestedProfile);
+				$sRequestedProfile = mb_strtolower($sRequestedProfile);
 				if (isset($aAllProfiles[$sRequestedProfile]))
 				{
 					$aProfiles[] = $aAllProfiles[$sRequestedProfile];
diff --git a/core/MyHelpers.class.inc.php b/core/MyHelpers.class.inc.php
index ece53ea7e..32aea4c26 100644
--- a/core/MyHelpers.class.inc.php
+++ b/core/MyHelpers.class.inc.php
@@ -521,6 +521,6 @@ class Str
 
 	public static function islowcase($sString)
 	{
-		return (strtolower($sString) == $sString);
+		return (mb_strtolower($sString) == $sString);
 	}
 }
diff --git a/core/attributedef.class.inc.php b/core/attributedef.class.inc.php
index 764dae3ab..e83a07f6b 100644
--- a/core/attributedef.class.inc.php
+++ b/core/attributedef.class.inc.php
@@ -3506,7 +3506,7 @@ class AttributeBoolean extends AttributeInteger
 		$sProposedValue, $bLocalizedValue = false, $sSepItem = null, $sSepAttribute = null, $sSepValue = null,
 		$sAttributeQualifier = null
 	) {
-		$sInput = strtolower(trim($sProposedValue));
+		$sInput = mb_strtolower(trim($sProposedValue));
 		if ($bLocalizedValue)
 		{
 			switch ($sInput)
diff --git a/datamodels/2.x/authent-cas/src/CASLoginExtension.php b/datamodels/2.x/authent-cas/src/CASLoginExtension.php
index acb6ab60b..1b7c7c288 100644
--- a/datamodels/2.x/authent-cas/src/CASLoginExtension.php
+++ b/datamodels/2.x/authent-cas/src/CASLoginExtension.php
@@ -488,7 +488,7 @@ class CASUserProvisioning
 		$aAllProfiles = array();
 		while($oProfile = $oProfilesSet->Fetch())
 		{
-			$aAllProfiles[strtolower($oProfile->GetName())] = $oProfile->GetKey();
+			$aAllProfiles[mb_strtolower($oProfile->GetName())] = $oProfile->GetKey();
 		}
 
 		// Translate the CAS/LDAP group names into iTop profile names
@@ -498,9 +498,9 @@ class CASUserProvisioning
 		{
 			if (preg_match($sPattern, $sGroupName, $aMatches))
 			{
-				if (array_key_exists(strtolower($aMatches[1]), $aAllProfiles))
+				if (array_key_exists(mb_strtolower($aMatches[1]), $aAllProfiles))
 				{
-					$aProfiles[] = $aAllProfiles[strtolower($aMatches[1])];
+					$aProfiles[] = $aAllProfiles[mb_strtolower($aMatches[1])];
 					phpCAS::log("Info: Adding the profile '{$aMatches[1]}' from CAS.");
 				}
 				else
@@ -522,10 +522,10 @@ class CASUserProvisioning
 			$aCASDefaultProfiles = explode(';', $sCASDefaultProfiles);
 			foreach($aCASDefaultProfiles as $sDefaultProfileName)
 			{
-				if (array_key_exists(strtolower($sDefaultProfileName), $aAllProfiles))
+				if (array_key_exists(mb_strtolower($sDefaultProfileName), $aAllProfiles))
 				{
-					$aProfiles[] = $aAllProfiles[strtolower($sDefaultProfileName)];
-					phpCAS::log("Info: Adding the default profile '".$aAllProfiles[strtolower($sDefaultProfileName)]."' from CAS.");
+					$aProfiles[] = $aAllProfiles[mb_strtolower($sDefaultProfileName)];
+					phpCAS::log("Info: Adding the default profile '".$aAllProfiles[mb_strtolower($sDefaultProfileName)]."' from CAS.");
 				}
 				else
 				{