diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 333ad68eb..3ec5ed202 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -96,20 +96,20 @@ RootValue allocRootValue(Value * v)
 }
 
 
-void printValue(std::ostream & str, std::set<const void *> & seen, const Value & v)
+void Value::print(std::ostream & str, std::set<const void *> * seen) const
 {
     checkInterrupt();
 
-    switch (v.internalType) {
+    switch (internalType) {
     case tInt:
-        str << v.integer;
+        str << integer;
         break;
     case tBool:
-        str << (v.boolean ? "true" : "false");
+        str << (boolean ? "true" : "false");
         break;
     case tString:
         str << "\"";
-        for (const char * i = v.string.s; *i; i++)
+        for (const char * i = string.s; *i; i++)
             if (*i == '\"' || *i == '\\') str << "\\" << *i;
             else if (*i == '\n') str << "\\n";
             else if (*i == '\r') str << "\\r";
@@ -119,19 +119,19 @@ void printValue(std::ostream & str, std::set<const void *> & seen, const Value &
         str << "\"";
         break;
     case tPath:
-        str << v.path; // !!! escaping?
+        str << path; // !!! escaping?
         break;
     case tNull:
         str << "null";
         break;
     case tAttrs: {
-        if (!v.attrs->empty() && !seen.insert(v.attrs).second)
+        if (seen && !attrs->empty() && !seen->insert(attrs).second)
             str << "«repeated»";
         else {
             str << "{ ";
-            for (auto & i : v.attrs->lexicographicOrder()) {
+            for (auto & i : attrs->lexicographicOrder()) {
                 str << i->name << " = ";
-                printValue(str, seen, *i->value);
+                i->value->print(str, seen);
                 str << "; ";
             }
             str << "}";
@@ -141,12 +141,12 @@ void printValue(std::ostream & str, std::set<const void *> & seen, const Value &
     case tList1:
     case tList2:
     case tListN:
-        if (v.listSize() && !seen.insert(v.listElems()).second)
+        if (seen && listSize() && !seen->insert(listElems()).second)
             str << "«repeated»";
         else {
             str << "[ ";
-            for (auto v2 : v.listItems()) {
-                printValue(str, seen, *v2);
+            for (auto v2 : listItems()) {
+                v2->print(str, seen);
                 str << " ";
             }
             str << "]";
@@ -166,10 +166,10 @@ void printValue(std::ostream & str, std::set<const void *> & seen, const Value &
         str << "<PRIMOP-APP>";
         break;
     case tExternal:
-        str << *v.external;
+        str << *external;
         break;
     case tFloat:
-        str << v.fpoint;
+        str << fpoint;
         break;
     default:
         abort();
@@ -177,10 +177,16 @@ void printValue(std::ostream & str, std::set<const void *> & seen, const Value &
 }
 
 
-std::ostream & operator << (std::ostream & str, const Value & v)
+void Value::print(std::ostream & str, bool showRepeated) const
 {
     std::set<const void *> seen;
-    printValue(str, seen, v);
+    print(str, showRepeated ? nullptr : &seen);
+}
+
+
+std::ostream & operator << (std::ostream & str, const Value & v)
+{
+    v.print(str, false);
     return str;
 }
 
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index d413060f9..3d07c3198 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -119,10 +119,13 @@ private:
     InternalType internalType;
 
     friend std::string showType(const Value & v);
-    friend void printValue(std::ostream & str, std::set<const void *> & seen, const Value & v);
+
+    void print(std::ostream & str, std::set<const void *> * seen) const;
 
 public:
 
+    void print(std::ostream & str, bool showRepeated = false) const;
+
     // Functions needed to distinguish the type
     // These should be removed eventually, by putting the functionality that's
     // needed by callers into methods of this type
diff --git a/src/nix-env/user-env.cc b/src/nix-env/user-env.cc
index bcc7736ac..78692b9c6 100644
--- a/src/nix-env/user-env.cc
+++ b/src/nix-env/user-env.cc
@@ -105,8 +105,10 @@ bool createUserEnv(EvalState & state, DrvInfos & elems,
     /* Also write a copy of the list of user environment elements to
        the store; we need it for future modifications of the
        environment. */
+    std::ostringstream str;
+    manifest.print(str, true);
     auto manifestFile = state.store->addTextToStore("env-manifest.nix",
-        fmt("%s", manifest), references);
+        str.str(), references);
 
     /* Get the environment builder expression. */
     Value envBuilder;
diff --git a/tests/user-envs.nix b/tests/user-envs.nix
index 6ac896ed8..46f8b51dd 100644
--- a/tests/user-envs.nix
+++ b/tests/user-envs.nix
@@ -8,6 +8,8 @@ assert foo == "foo";
 
 let
 
+  platforms = let x = "foobar"; in [ x x ];
+
   makeDrv = name: progName: (mkDerivation {
     name = assert progName != "fail"; name;
     inherit progName system;
@@ -15,6 +17,7 @@ let
   } // {
     meta = {
       description = "A silly test package with some \${escaped anti-quotation} in it";
+      inherit platforms;
     };
   });