diff --git a/configure.ac b/configure.ac
index 03819db8..11a817a2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -10,6 +10,8 @@ AC_PROG_LN_S
 AC_PROG_LIBTOOL
 AC_PROG_CXX
 
+CXXFLAGS+=" -std=c++0x"
+
 dnl Optional dependencies to build the manual, normally not needed
 dnl since the tarball comes with the PDF and HTML manuals.
 AC_PATH_PROG([DBLATEX], [dblatex])
diff --git a/src/c/hydra-eval-jobs.cc b/src/c/hydra-eval-jobs.cc
index cc4a0eed..21ca3917 100644
--- a/src/c/hydra-eval-jobs.cc
+++ b/src/c/hydra-eval-jobs.cc
@@ -156,7 +156,7 @@ static void findJobsWrapped(EvalState & state, XMLWriter & doc,
                 if (a == v.attrs->end())
                     throw EvalError("derivation must have a ‘constituents’ attribute");
                 PathSet context;
-                state.coerceToString(*a->value, context, true, false);
+                state.coerceToString(*a->pos, *a->value, context, true, false);
                 PathSet drvs;
                 foreach (PathSet::iterator, i, context)
                     if (i->at(0) == '!') {