diff --git a/SpineViewer/Dialogs/ProgressDialog.cs b/SpineViewer/Dialogs/ProgressDialog.cs
index 560d946..ba00b1e 100644
--- a/SpineViewer/Dialogs/ProgressDialog.cs
+++ b/SpineViewer/Dialogs/ProgressDialog.cs
@@ -14,7 +14,7 @@ namespace SpineViewer.Dialogs
 {
     public partial class ProgressDialog : Form
     {
-        private Logger logger = LogManager.GetCurrentClassLogger();
+        private readonly Logger logger = LogManager.GetCurrentClassLogger();
 
         public ProgressDialog()
         {
diff --git a/SpineViewer/Forms/SpineViewerForm.cs b/SpineViewer/Forms/SpineViewerForm.cs
index 7a7dc30..5468092 100644
--- a/SpineViewer/Forms/SpineViewerForm.cs
+++ b/SpineViewer/Forms/SpineViewerForm.cs
@@ -12,7 +12,7 @@ namespace SpineViewer
 {
     internal partial class SpineViewerForm : Form
     {
-        private Logger logger = LogManager.GetCurrentClassLogger();
+        private readonly Logger logger = LogManager.GetCurrentClassLogger();
 
         public SpineViewerForm()
         {