4 files changed, 14 insertions, 4 deletions
diff --git a/src/libexpr/eval-inline.hh b/src/libexpr/eval-inline.hh
index c8d83814f3ca..0748fbd3f3e1 100644
--- a/src/libexpr/eval-inline.hh
+++ b/src/libexpr/eval-inline.hh
@@ -78,5 +78,4 @@ inline void EvalState::forceList(Value & v, const Pos & pos)
         throwTypeError("value is %1% while a list was expected, at %2%", v, pos);
 }
 
-
 }
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 74f88e498fed..acf1fbdc1356 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1291,10 +1291,16 @@ bool EvalState::forceBool(Value & v)
 }
 
 
+bool EvalState::isFunctor(Value & fun)
+{
+    return fun.type == tAttrs && fun.attrs->find(sFunctor) != fun.attrs->end();
+}
+
+
 void EvalState::forceFunction(Value & v, const Pos & pos)
 {
     forceValue(v);
-    if (v.type != tLambda && v.type != tPrimOp && v.type != tPrimOpApp)
+    if (v.type != tLambda && v.type != tPrimOp && v.type != tPrimOpApp && !isFunctor(v))
         throwTypeError("value is %1% while a function was expected, at %2%", v, pos);
 }
 
@@ -1386,7 +1392,7 @@ string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
            shell scripting convenience, just like `null'. */
         if (v.type == tBool && v.boolean) return "1";
         if (v.type == tBool && !v.boolean) return "";
-        if (v.type == tInt) return int2String(v.integer);
+        if (v.type == tInt) return std::to_string(v.integer);
         if (v.type == tNull) return "";
 
         if (v.isList()) {
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 8df0084fd57a..eb55f6d4d431 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -213,6 +213,8 @@ public:
        elements and attributes are compared recursively. */
     bool eqValues(Value & v1, Value & v2);
 
+    bool isFunctor(Value & fun);
+
     void callFunction(Value & fun, Value & arg, Value & v, const Pos & pos);
     void callPrimOp(Value & fun, Value & arg, Value & v, const Pos & pos);
 
diff --git a/src/libexpr/local.mk b/src/libexpr/local.mk
index d1b1987fb037..5de9ccc6d011 100644
--- a/src/libexpr/local.mk
+++ b/src/libexpr/local.mk
@@ -10,7 +10,10 @@ libexpr_CXXFLAGS := -Wno-deprecated-register
 
 libexpr_LIBS = libutil libstore libformat
 
-libexpr_LDFLAGS = -ldl
+libexpr_LDFLAGS =
+ifneq ($(OS), FreeBSD)
+ libexpr_LDFLAGS += -ldl
+endif
 
 # The dependency on libgc must be propagated (i.e. meaning that
 # programs/libraries that use libexpr must explicitly pass -lgc),