diff --git a/third_party/nix/src/libstore/derivations.cc b/third_party/nix/src/libstore/derivations.cc
index 7a0de8f06..a46d07967 100644
--- a/third_party/nix/src/libstore/derivations.cc
+++ b/third_party/nix/src/libstore/derivations.cc
@@ -200,8 +200,8 @@ static void printString(string& res, const string& s) {
     } else {
       res += *i;
     }
-    res += '"';
   }
+  res += '"';
 }
 
 template <class ForwardIterator>