diff --git a/src/util/subprocess.h b/src/util/subprocess.h
index 91f84a290bd..6fa84af2af7 100644
--- a/src/util/subprocess.h
+++ b/src/util/subprocess.h
@@ -171,6 +171,7 @@ public:
 //--------------------------------------------------------------------
 namespace util
 {
+#ifdef __USING_WINDOWS__
   inline void quote_argument(const std::wstring &argument, std::wstring &command_line,
                       bool force)
   {
@@ -181,7 +182,7 @@ namespace util
     //
 
     if (force == false && argument.empty() == false &&
-        argument.find_first_of(L" \t\n\v\"") == argument.npos) {
+        argument.find_first_of(L" \t\n\v") == argument.npos) {
       command_line.append(argument);
     }
     else {
@@ -231,7 +232,6 @@ namespace util
     }
   }
 
-#ifdef __USING_WINDOWS__
   inline std::string get_last_error(DWORD errorMessageID)
   {
     if (errorMessageID == 0)