diff --git a/src/KeyChain.Net.XamarinAndroid/KeyChainHelper.cs b/src/KeyChain.Net.XamarinAndroid/KeyChainHelper.cs
index a7d5807..8d43b11 100644
--- a/src/KeyChain.Net.XamarinAndroid/KeyChainHelper.cs
+++ b/src/KeyChain.Net.XamarinAndroid/KeyChainHelper.cs
@@ -76,12 +76,12 @@ public KeyChainHelper(Func<Context> context, string keyStoreFileProtectionPasswo
 		/// <param name="keyName">Keyname/username.</param>
 		public string GetKey (string keyName)
 		{
-			var wantedAlias = MakeAlias(keyName, _serviceId).ToLower();
+			var wantedAlias = MakeAlias(keyName, _serviceId).ToLowerInvariant();
 
 			var aliases = _androidKeyStore.Aliases ();
 			while (aliases.HasMoreElements) {
 				var alias = aliases.NextElement ().ToString ();
-				if (alias.ToLower().Contains(wantedAlias)) 
+				if (alias.ToLowerInvariant().Contains(wantedAlias)) 
 				{
 					var e = _androidKeyStore.GetEntry (alias, _passwordProtection) as KeyStore.SecretKeyEntry;
 					if (e != null) 
diff --git a/src/KeyChain.Net.XamarinIOS/KeyChainHelper.cs b/src/KeyChain.Net.XamarinIOS/KeyChainHelper.cs
index e6cd490..3da7728 100644
--- a/src/KeyChain.Net.XamarinIOS/KeyChainHelper.cs
+++ b/src/KeyChain.Net.XamarinIOS/KeyChainHelper.cs
@@ -92,8 +92,8 @@ private static SecStatusCode DeletePassword (string username, string serviceId,
 			}
 			
 			// Querying is case sesitive - we don't want that.
-			username = username.ToLower (  );
-			serviceId = serviceId.ToLower (  );
+			username = username.ToLowerInvariant (  );
+			serviceId = serviceId.ToLowerInvariant (  );
 			
 			// Query and remove.
 			SecRecord queryRec = new SecRecord ( SecKind.GenericPassword ) { Service = serviceId, Label = serviceId, Account = username, Synchronizable = synchronizable };
@@ -128,8 +128,8 @@ private static SecStatusCode SetPassword ( string username, string password, str
 			}
 			
 			// Querying is case sesitive - we don't want that.
-			username = username.ToLower (  );
-			serviceId = serviceId.ToLower (  );
+			username = username.ToLowerInvariant (  );
+			serviceId = serviceId.ToLowerInvariant (  );
 			
 			// Don't bother updating. Delete existing record and create a new one.
 			DeletePassword ( username, serviceId, synchronizable );
@@ -173,8 +173,8 @@ private static string GetPassword ( string username, string serviceId, bool sync
 			}
 			
 			// Querying is case sesitive - we don't want that.
-			username = username.ToLower (  );
-			serviceId = serviceId.ToLower (  );
+			username = username.ToLowerInvariant (  );
+			serviceId = serviceId.ToLowerInvariant (  );
 			
 			SecStatusCode code;
 			// Query the record.