diff --git a/.semver.txt b/.semver.txt
index 15245f3..e8eb7f1 100644
--- a/.semver.txt
+++ b/.semver.txt
@@ -1 +1 @@
-1.0.32
+1.0.33
diff --git a/src/JiraTimeBot/JiraTimeBot.csproj b/src/JiraTimeBot/JiraTimeBot.csproj
index ca04000..f8efc9e 100644
--- a/src/JiraTimeBot/JiraTimeBot.csproj
+++ b/src/JiraTimeBot/JiraTimeBot.csproj
@@ -116,6 +116,7 @@
     <Compile Include="UI\frmSettings.Designer.cs">
       <DependentUpon>frmSettings.cs</DependentUpon>
     </Compile>
+    <Compile Include="UI\Tray\SingleInstance.cs" />
     <Compile Include="UI\Tray\ITrayMenu.cs" />
     <Compile Include="UI\Tray\RestoreFromTray.cs" />
     <Compile Include="UI\Tray\TrayMenu.cs" />
diff --git a/src/JiraTimeBot/Program.cs b/src/JiraTimeBot/Program.cs
index e126dac..f333ff1 100644
--- a/src/JiraTimeBot/Program.cs
+++ b/src/JiraTimeBot/Program.cs
@@ -4,6 +4,7 @@ using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Windows.Forms;
+using JiraTimeBot.UI.Tray;
 
 namespace JiraTimeBot
 {
@@ -25,7 +26,7 @@ namespace JiraTimeBot
             }
             else
             {
-                MessageBox.Show("Another instance of the app is already running.");
+                SingleInstance.ShowFirstInstance();
             }
         }
     }
diff --git a/src/JiraTimeBot/Properties/AssemblyInfo.cs b/src/JiraTimeBot/Properties/AssemblyInfo.cs
index 0feb50c..896fe5a 100644
--- a/src/JiraTimeBot/Properties/AssemblyInfo.cs
+++ b/src/JiraTimeBot/Properties/AssemblyInfo.cs
@@ -1,31 +1,31 @@
-using System.Reflection;                       
-using System.Runtime.InteropServices;                       
-// General Information about an assembly is controlled through the following                       
-// set of attributes. Change these attribute values to modify the information                       
-// associated with an assembly.                       
-[assembly: AssemblyTitle("JiraTimeBot")]                       
-[assembly: AssemblyDescription("")]                       
-[assembly: AssemblyConfiguration("")]                       
-[assembly: AssemblyCompany("")]                       
-[assembly: AssemblyProduct("JiraTimeBot")]                       
-[assembly: AssemblyCopyright("Copyright © 2019")]                       
-[assembly: AssemblyTrademark("")]                       
-[assembly: AssemblyCulture("")]                       
-// Setting ComVisible to false makes the types in this assembly not visible                       
-// to COM components.  If you need to access a type in this assembly from                       
-// COM, set the ComVisible attribute to true on that type.                       
-[assembly: ComVisible(false)]                       
-// The following GUID is for the ID of the typelib if this project is exposed to COM                       
-[assembly: Guid("f3b89316-c38c-4ce6-9d88-0b1373cfba1a")]                       
-// Version information for an assembly consists of the following four values:                       
-//                       
-//      Major Version                       
-//      Minor Version                       
-//      Build Number                       
-//      Revision                       
-//                       
-// You can specify all the values or you can default the Build and Revision Numbers                       
-// by using the '*' as shown below:                       
-[assembly: AssemblyVersion("1.0.32")] 
-[assembly: AssemblyFileVersion("1.0.32")] 
-[assembly: AssemblyInformationalVersion("1.0.32")] 
+using System.Reflection;                        
+using System.Runtime.InteropServices;                        
+// General Information about an assembly is controlled through the following                        
+// set of attributes. Change these attribute values to modify the information                        
+// associated with an assembly.                        
+[assembly: AssemblyTitle("JiraTimeBot")]                        
+[assembly: AssemblyDescription("")]                        
+[assembly: AssemblyConfiguration("")]                        
+[assembly: AssemblyCompany("")]                        
+[assembly: AssemblyProduct("JiraTimeBot")]                        
+[assembly: AssemblyCopyright("Copyright © 2019")]                        
+[assembly: AssemblyTrademark("")]                        
+[assembly: AssemblyCulture("")]                        
+// Setting ComVisible to false makes the types in this assembly not visible                        
+// to COM components.  If you need to access a type in this assembly from                        
+// COM, set the ComVisible attribute to true on that type.                        
+[assembly: ComVisible(false)]                        
+// The following GUID is for the ID of the typelib if this project is exposed to COM                        
+[assembly: Guid("f3b89316-c38c-4ce6-9d88-0b1373cfba1a")]                        
+// Version information for an assembly consists of the following four values:                        
+//                        
+//      Major Version                        
+//      Minor Version                        
+//      Build Number                        
+//      Revision                        
+//                        
+// You can specify all the values or you can default the Build and Revision Numbers                        
+// by using the '*' as shown below:                        
+[assembly: AssemblyVersion("1.0.33")] 
+[assembly: AssemblyFileVersion("1.0.33")] 
+[assembly: AssemblyInformationalVersion("1.0.33")] 
diff --git a/src/JiraTimeBot/UI/Tray/SingleInstance.cs b/src/JiraTimeBot/UI/Tray/SingleInstance.cs
new file mode 100644
index 0000000..8a4f6f3
--- /dev/null
+++ b/src/JiraTimeBot/UI/Tray/SingleInstance.cs
@@ -0,0 +1,35 @@
+using System;
+using System.Reflection;
+using System.Runtime.InteropServices;
+
+namespace JiraTimeBot.UI.Tray
+{
+    static class SingleInstance
+    {
+        public static readonly int WM_SHOWFIRSTINSTANCE = RegisterWindowMessage($"WM_SHOWFIRSTINSTANCE|{AssemblyGuid}");
+        
+        public static void ShowFirstInstance()
+        {
+            const int HWND_BROADCAST = 0xffff;
+            PostMessage((IntPtr)HWND_BROADCAST, WM_SHOWFIRSTINSTANCE, IntPtr.Zero, IntPtr.Zero);
+        }
+        
+        public static string AssemblyGuid
+        {
+            get
+            {
+                object[] attributes = Assembly.GetEntryAssembly().GetCustomAttributes(typeof(System.Runtime.InteropServices.GuidAttribute), false);
+                if (attributes.Length == 0) {
+                    return string.Empty;
+                }
+                return ((GuidAttribute)attributes[0]).Value;
+            }
+        }
+        
+        [DllImport("user32")]
+        public static extern int RegisterWindowMessage(string message);
+	
+        [DllImport("user32")]
+        public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
+    }
+}
diff --git a/src/JiraTimeBot/UI/frmMain.cs b/src/JiraTimeBot/UI/frmMain.cs
index 973edad..8a67f27 100644
--- a/src/JiraTimeBot/UI/frmMain.cs
+++ b/src/JiraTimeBot/UI/frmMain.cs
@@ -31,6 +31,16 @@ namespace JiraTimeBot.UI
         private readonly Action<string> _settingsErrorReporter;
         private bool _updateChecked;
 
+        protected override void WndProc(ref Message message)
+        {
+            if (message.Msg == SingleInstance.WM_SHOWFIRSTINSTANCE) {
+                this.Show();
+                this.WindowState = FormWindowState.Normal;
+                _trayIcon.Hide();
+            }
+            base.WndProc(ref message);
+        }
+
         private CancellationTokenSource GetTokenSource()
         {
             var tokenSource = new CancellationTokenSource();