diff --git a/interface/wx/ffile.h b/interface/wx/ffile.h
index 75a9df5260..54ed7ca759 100644
--- a/interface/wx/ffile.h
+++ b/interface/wx/ffile.h
@@ -48,6 +48,13 @@
 class wxTempFFile
 {
 public:
+    /**
+        Default constructor doesn't do anything.
+
+        Call Open() later.
+     */
+    wxTempFFile();
+
     /**
         Associates wxTempFFile with the file to be replaced and opens it.
 
diff --git a/interface/wx/file.h b/interface/wx/file.h
index 6be40318e9..887cce2f01 100644
--- a/interface/wx/file.h
+++ b/interface/wx/file.h
@@ -46,6 +46,13 @@
 class wxTempFile
 {
 public:
+    /**
+        Default constructor doesn't do anything.
+
+        Call Open() later.
+     */
+    wxTempFile();
+
     /**
         Associates wxTempFile with the file to be replaced and opens it.