diff --git a/subprocess.hpp b/subprocess.hpp
index 826cd9c..3975eb6 100755
--- a/subprocess.hpp
+++ b/subprocess.hpp
@@ -193,7 +193,7 @@ 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 {