diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 8aef85dc5..29daabe49 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -2051,7 +2051,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
     else if (firstType == nPath) {
         if (!context.empty())
             state.error<EvalError>("a string that refers to a store path cannot be appended to a path").atPos(pos).withFrame(env, *this).debugThrow();
-        v.mkPath(state.rootPath(CanonPath(canonPath(str()))));
+        v.mkPath(state.rootPath(CanonPath(str())));
     } else
         v.mkStringMove(c_str(), context);
 }