diff --git a/src/NAppUpdate.Framework/Tasks/FileUpdateTask.cs b/src/NAppUpdate.Framework/Tasks/FileUpdateTask.cs
index 61278b5a..ba9f82da 100644
--- a/src/NAppUpdate.Framework/Tasks/FileUpdateTask.cs
+++ b/src/NAppUpdate.Framework/Tasks/FileUpdateTask.cs
@@ -76,15 +76,21 @@ public override TaskExecutionStatus Execute(bool coldRun)
 			}
 
 			var dirName = Path.GetDirectoryName(_destinationFile);
+
 			if (!Directory.Exists(dirName))
+			{
 				Utils.FileSystem.CreateDirectoryStructure(dirName, false);
+			}
 
 			// Create a backup copy if target exists
 			if (_backupFile == null && File.Exists(_destinationFile))
 			{
 				if (!Directory.Exists(Path.GetDirectoryName(Path.Combine(UpdateManager.Instance.Config.BackupFolder, LocalPath))))
-					Utils.FileSystem.CreateDirectoryStructure(
-						Path.GetDirectoryName(Path.Combine(UpdateManager.Instance.Config.BackupFolder, LocalPath)), false);
+				{
+					string backupPath = Path.GetDirectoryName(Path.Combine(UpdateManager.Instance.Config.BackupFolder, LocalPath));
+					Utils.FileSystem.CreateDirectoryStructure(backupPath, false);
+				}
+
 				_backupFile = Path.Combine(UpdateManager.Instance.Config.BackupFolder, LocalPath);
 				File.Copy(_destinationFile, _backupFile, true);
 			}
@@ -94,11 +100,7 @@ public override TaskExecutionStatus Execute(bool coldRun)
 			{
 				if (File.Exists(_destinationFile))
 				{
-					//if (FileSystem.IsExeRunning(_destinationFile))
-					//{
-					//    UpdateManager.Instance.Logger.Log(Logger.SeverityLevel.Warning, "Process {0} is still running", _destinationFile);
-					//    Thread.Sleep(1000); // TODO: retry a few times and throw after a while
-					//}
+					FileLockWait();
 
 					if (!PermissionsCheck.HaveWritePermissionsForFileOrFolder(_destinationFile))
 					{
@@ -114,7 +116,10 @@ public override TaskExecutionStatus Execute(bool coldRun)
 				try
 				{
 					if (File.Exists(_destinationFile))
+					{
 						File.Delete(_destinationFile);
+					}
+
 					File.Move(_tempFile, _destinationFile);
 					_tempFile = null;
 				}
@@ -155,5 +160,23 @@ public override bool Rollback()
 
 			return true;
 		}
+
+		/// <summary>
+		/// To mitigate problems with the files being locked even though the application mutex has been released.
+		/// https://github.com/synhershko/NAppUpdate/issues/35
+		/// </summary>
+		private void FileLockWait()
+		{
+			int attempt = 0;
+			while (FileSystem.IsFileLocked(new FileInfo(_destinationFile)))
+			{
+				Thread.Sleep(500);
+				attempt++;
+				if (attempt == 10)
+				{
+					throw new UpdateProcessFailedException("Failed to update, the file is locked: " + _destinationFile);
+				}
+			}
+		}
 	}
 }
diff --git a/src/NAppUpdate.Framework/Utils/FileSystem.cs b/src/NAppUpdate.Framework/Utils/FileSystem.cs
index 4e5ba459..3cfdde43 100644
--- a/src/NAppUpdate.Framework/Utils/FileSystem.cs
+++ b/src/NAppUpdate.Framework/Utils/FileSystem.cs
@@ -65,16 +65,36 @@ public static IEnumerable<string> GetFiles(string path, string searchPattern, Se
 			return files;
 		}
 
-		public static bool IsExeRunning(string path)
+		/// <summary>
+		/// Returns true if read/write lock exists on the file, otherwise false
+		/// From http://stackoverflow.com/a/937558
+		/// </summary>
+		/// <param name="file">The file to check for a lock</param>
+		/// <returns></returns>
+		public static bool IsFileLocked(FileInfo file)
 		{
-			var processes = Process.GetProcesses();
-			foreach (Process p in processes)
+			FileStream stream = null;
+
+			try
+			{
+				stream = file.Open(FileMode.Open, FileAccess.ReadWrite, FileShare.None);
+			}
+			catch (IOException)
 			{
-				if (p.MainModule.FileName.StartsWith(path, StringComparison.InvariantCultureIgnoreCase))
-					return true;
+				//the file is unavailable because it is:
+				//still being written to
+				//or being processed by another thread
+				//or does not exist (has already been processed)
+				return true;
 			}
+			finally
+			{
+				if (stream != null)
+					stream.Close();
+			}
+
+			//file is not locked
 			return false;
 		}
-
 	}
 }