diff --git a/src/native_text.cpp b/src/native_text.cpp
index b5d9d0e..6597d6f 100644
--- a/src/native_text.cpp
+++ b/src/native_text.cpp
@@ -25,12 +25,15 @@
 #include <sys/cygwin.h>
 #endif
 
-namespace quickbook {
-    extern bool ms_errors;
-}
-
 namespace quickbook {
 namespace detail {
+    namespace {
+        bool ms_errors = false;
+    }
+
+    void set_ms_errors(bool x) {
+        ms_errors = x;
+    }
 
 // This is used for converting paths to UTF-8 on cygin.
 // Might be better not to use a windows 
@@ -113,7 +116,7 @@ namespace detail {
     // https://en.wikipedia.org/wiki/File_URI_scheme
     std::string file_path_to_url(fs::path const& x)
     {
-        // TODO: Maybe should throw an exception if this doesn't understand the path.
+        // TODO: Maybe some kind of error if this doesn't understand the path.
         // TODO: Might need a special cygwin implementation.
         // TODO: What if x.has_root_name() && !x.has_root_directory()?
         // TODO: What does Boost.Filesystem do for '//localhost/c:/path'?
diff --git a/src/native_text.hpp b/src/native_text.hpp
index f38f311..7d8f56a 100644
--- a/src/native_text.hpp
+++ b/src/native_text.hpp
@@ -132,9 +132,10 @@ namespace quickbook
         ostream& out();
 
         // Preformats an error/warning message so that it can be parsed by
-        // common IDEs. Uses the ms_errors global to determine if VS format
+        // common IDEs. Set 'ms_errors' to determine if VS format
         // or GCC format. Returns the stream to continue ouput of the verbose
         // error message.
+        void set_ms_errors(bool);
         ostream& outerr();
         ostream& outerr(fs::path const& file, int line = -1);
         ostream& outwarn(fs::path const& file, int line = -1);
diff --git a/src/quickbook.cpp b/src/quickbook.cpp
index 8c028be..3447a46 100644
--- a/src/quickbook.cpp
+++ b/src/quickbook.cpp
@@ -51,7 +51,6 @@ namespace quickbook
     tm* current_gm_time; // the current UTC time
     bool debug_mode; // for quickbook developers only
     bool self_linked_headers;
-    bool ms_errors = false; // output errors/warnings as if for VS
     std::vector<fs::path> include_path;
     std::vector<std::string> preset_defines;
     fs::path image_location;
@@ -378,8 +377,7 @@ main(int argc, char* argv[])
             return 0;
         }
 
-        if (vm.count("ms-errors"))
-            quickbook::ms_errors = true;
+        quickbook::detail::set_ms_errors(vm.count("ms-errors"));
 
         if (vm.count("no-pretty-print"))
             parse_document_options.pretty_print = false;