diff --git a/simgear/misc/sg_path.cxx b/simgear/misc/sg_path.cxx
index 8e361e84..c01928e8 100644
--- a/simgear/misc/sg_path.cxx
+++ b/simgear/misc/sg_path.cxx
@@ -53,9 +53,10 @@
 using std::string;
 using simgear::strutils::starts_with;
 
-// For SGPath::validate()
-static string_list read_allowed_paths;
-static string_list write_allowed_paths;
+// Static data members used by SGPath::addAllowedPathPattern(),
+// SGPath::validate(), etc.
+string_list SGPath::read_allowed_paths;
+string_list SGPath::write_allowed_paths;
 
 /**
  * define directory path separators
diff --git a/simgear/misc/sg_path.hxx b/simgear/misc/sg_path.hxx
index d11ea01a..973d796e 100644
--- a/simgear/misc/sg_path.hxx
+++ b/simgear/misc/sg_path.hxx
@@ -391,6 +391,10 @@ private:
     mutable bool _existsCached : 1; ///< only used on Windows
     mutable time_t _modTime;
     mutable size_t _size;
+
+    // For addAllowedPathPattern(), validate(), etc.
+    static string_list read_allowed_paths;
+    static string_list write_allowed_paths;
 };
 
 // Other comparison operators are in the class definition block