diff --git a/scripts/test-react.js b/scripts/test-react.js
index 6d76254c8..0361edc80 100644
--- a/scripts/test-react.js
+++ b/scripts/test-react.js
@@ -142,6 +142,10 @@ function runTestSuite(outputJsx) {
         await runTest(directory, "simple-5.js");
       });
 
+      it("Simple 6", async () => {
+        await runTest(directory, "simple-6.js");
+      });
+
       it("Simple children", async () => {
         await runTest(directory, "simple-children.js");
       });
diff --git a/src/evaluators/CallExpression.js b/src/evaluators/CallExpression.js
index ed611e8a0..0b75b51a4 100644
--- a/src/evaluators/CallExpression.js
+++ b/src/evaluators/CallExpression.js
@@ -98,6 +98,76 @@ function callBothFunctionsAndJoinTheirEffects(
   return completion;
 }
 
+function generateRuntimeCall(
+  ref: Value | Reference,
+  func: Value,
+  ast: BabelNodeCallExpression,
+  strictCode: boolean,
+  env: LexicalEnvironment,
+  realm: Realm
+) {
+  let args = [func];
+  let [thisArg, propName] = ref instanceof Reference ? [ref.base, ref.referencedName] : [];
+  if (thisArg instanceof Value) args = [thisArg];
+  if (propName !== undefined && typeof propName !== "string") args.push(propName);
+  args = args.concat(ArgumentListEvaluation(realm, strictCode, env, ast.arguments));
+  for (let arg of args) {
+    if (arg !== func) {
+      Leak.leakValue(realm, arg, ast.loc);
+    }
+  }
+  return AbstractValue.createTemporalFromBuildFunction(realm, Value, args, nodes => {
+    let callFunc;
+    let argStart = 1;
+    if (thisArg instanceof Value) {
+      if (typeof propName === "string") {
+        callFunc = t.memberExpression(nodes[0], t.identifier(propName), !t.isValidIdentifier(propName));
+      } else {
+        callFunc = t.memberExpression(nodes[0], nodes[1], true);
+        argStart = 2;
+      }
+    } else {
+      callFunc = nodes[0];
+    }
+    let fun_args = ((nodes.slice(argStart): any): Array<BabelNodeExpression | BabelNodeSpreadElement>);
+    return t.callExpression(callFunc, fun_args);
+  });
+}
+
+function tryToEvaluateCallOrLeaveAsAbstract(
+  ref: Value | Reference,
+  func: Value,
+  ast: BabelNodeCallExpression,
+  strictCode: boolean,
+  env: LexicalEnvironment,
+  realm: Realm,
+  thisValue: Value,
+  tailCall: boolean
+): Value {
+  let effects;
+  try {
+    effects = realm.evaluateForEffects(() =>
+      EvaluateDirectCall(realm, strictCode, env, ref, func, thisValue, ast.arguments, tailCall)
+    );
+  } catch (error) {
+    if (error instanceof FatalError) {
+      return realm.evaluateWithPossibleThrowCompletion(
+        () => generateRuntimeCall(ref, func, ast, strictCode, env, realm),
+        TypesDomain.topVal,
+        ValuesDomain.topVal
+      );
+    } else {
+      throw error;
+    }
+  }
+  realm.applyEffects(effects);
+  let completion = effects[0];
+  // return or throw completion
+  if (completion instanceof AbruptCompletion) throw completion;
+  invariant(completion instanceof Value);
+  return completion;
+}
+
 function EvaluateCall(
   ref: Value | Reference,
   func: Value,
@@ -106,35 +176,6 @@ function EvaluateCall(
   env: LexicalEnvironment,
   realm: Realm
 ): Value {
-  function generateRuntimeCall() {
-    let args = [func];
-    let [thisArg, propName] = ref instanceof Reference ? [ref.base, ref.referencedName] : [];
-    if (thisArg instanceof Value) args = [thisArg];
-    if (propName !== undefined && typeof propName !== "string") args.push(propName);
-    args = args.concat(ArgumentListEvaluation(realm, strictCode, env, ast.arguments));
-    for (let arg of args) {
-      if (arg !== func) {
-        Leak.leakValue(realm, arg, ast.loc);
-      }
-    }
-    return AbstractValue.createTemporalFromBuildFunction(realm, Value, args, nodes => {
-      let callFunc;
-      let argStart = 1;
-      if (thisArg instanceof Value) {
-        if (typeof propName === "string") {
-          callFunc = t.memberExpression(nodes[0], t.identifier(propName), !t.isValidIdentifier(propName));
-        } else {
-          callFunc = t.memberExpression(nodes[0], nodes[1], true);
-          argStart = 2;
-        }
-      } else {
-        callFunc = nodes[0];
-      }
-      let fun_args = ((nodes.slice(argStart): any): Array<BabelNodeExpression | BabelNodeSpreadElement>);
-      return t.callExpression(callFunc, fun_args);
-    });
-  }
-
   if (func instanceof AbstractValue) {
     let loc = ast.callee.type === "MemberExpression" ? ast.callee.property.loc : ast.callee.loc;
     if (!Value.isTypeCompatibleWith(func.getType(), FunctionValue)) {
@@ -151,9 +192,13 @@ function EvaluateCall(
     }
     if (realm.isInPureScope()) {
       // In pure functions we allow abstract functions to throw, which this might.
-      return realm.evaluateWithPossibleThrowCompletion(generateRuntimeCall, TypesDomain.topVal, ValuesDomain.topVal);
+      return realm.evaluateWithPossibleThrowCompletion(
+        () => generateRuntimeCall(ref, func, ast, strictCode, env, realm),
+        TypesDomain.topVal,
+        ValuesDomain.topVal
+      );
     }
-    return generateRuntimeCall();
+    return generateRuntimeCall(ref, func, ast, strictCode, env, realm);
   }
   invariant(func instanceof ConcreteValue);
 
@@ -181,7 +226,7 @@ function EvaluateCall(
         let error = new CompilerDiagnostic("eval argument must be a known value", loc, "PP0006", "RecoverableError");
         if (realm.handleError(error) === "Fail") throw new FatalError();
         // Assume that it is a safe eval with no visible heap changes or abrupt control flow.
-        return generateRuntimeCall();
+        return generateRuntimeCall(ref, func, ast, strictCode, env, realm);
       }
       return Functions.PerformEval(realm, evalText, evalRealm, strictCaller, true);
     }
@@ -217,5 +262,9 @@ function EvaluateCall(
   let tailCall = IsInTailPosition(realm, thisCall);
 
   // 8. Return ? EvaluateDirectCall(func, thisValue, Arguments, tailCall).
-  return EvaluateDirectCall(realm, strictCode, env, ref, func, thisValue, ast.arguments, tailCall);
+  if (realm.isInPureScope()) {
+    return tryToEvaluateCallOrLeaveAsAbstract(ref, func, ast, strictCode, env, realm, thisValue, tailCall);
+  } else {
+    return EvaluateDirectCall(realm, strictCode, env, ref, func, thisValue, ast.arguments, tailCall);
+  }
 }
diff --git a/src/serializer/ResidualHeapSerializer.js b/src/serializer/ResidualHeapSerializer.js
index b9b91c792..dfceecb30 100644
--- a/src/serializer/ResidualHeapSerializer.js
+++ b/src/serializer/ResidualHeapSerializer.js
@@ -1737,7 +1737,6 @@ export class ResidualHeapSerializer {
     invariant(this.emitter._declaredAbstractValues.size <= this.preludeGenerator.derivedIds.size);
 
     this.postGeneratorSerialization();
-    Array.prototype.push.apply(this.prelude, this.preludeGenerator.prelude);
 
     // TODO #20: add timers
 
@@ -1749,6 +1748,8 @@ export class ResidualHeapSerializer {
     // Make sure additional functions get serialized.
     let rewrittenAdditionalFunctions = this.processAdditionalFunctionValues();
 
+    Array.prototype.push.apply(this.prelude, this.preludeGenerator.prelude);
+
     this.modules.resolveInitializedModules();
 
     this.emitter.finalize();
diff --git a/test/error-handler/try-and-call-abstract-function.js b/test/error-handler/try-and-call-abstract-function.js
index c7c113399..13d776c65 100644
--- a/test/error-handler/try-and-call-abstract-function.js
+++ b/test/error-handler/try-and-call-abstract-function.js
@@ -1,6 +1,7 @@
 // additional functions
 // abstract effects
-// expected errors: [{location: {"start":{"line":26,"column":11},"end":{"line":26,"column":21},"identifierName":"abstractFn","source":"test/error-handler/try-and-call-abstract-function.js"}, errorCode: "PP0021", severity: "RecoverableError", message: "Possible throw inside try/catch is not yet supported"}]
+// expected errors: [{location: {"start":{"line":27,"column":11},"end":{"line":27,"column":21},"identifierName":"abstractFn","source":"test/error-handler/try-and-call-abstract-function.js"}, errorCode: "PP0021", severity: "RecoverableError", message: "Possible throw inside try/catch is not yet supported"}]
+// recover-from-errors
 
 let abstractFn = global.__abstract ? __abstract('function', '(function() { return true; })') : function() { return true; };
 
diff --git a/test/react/functional-components/simple-6.js b/test/react/functional-components/simple-6.js
new file mode 100644
index 000000000..857f99c17
--- /dev/null
+++ b/test/react/functional-components/simple-6.js
@@ -0,0 +1,20 @@
+var React = require('react');
+// the JSX transform converts to React, so we need to add it back in
+this['React'] = React;
+
+function App(props) {
+  return (
+    <div>{String(props.title)}</div>
+  );
+}
+
+App.getTrials = function(renderer, Root) {
+  renderer.update(<Root />);
+  return [['simple render', renderer.toJSON()]];
+};
+
+if (this.__registerReactComponentRoot) {
+  __registerReactComponentRoot(App);
+}
+
+module.exports = App;
\ No newline at end of file
diff --git a/test/serializer/pure-functions/CastStringOnUnknown.js b/test/serializer/pure-functions/CastStringOnUnknown.js
new file mode 100644
index 000000000..9ca70ddee
--- /dev/null
+++ b/test/serializer/pure-functions/CastStringOnUnknown.js
@@ -0,0 +1,22 @@
+// additional functions
+// abstract effects
+
+let obj1 = global.__abstract ? __abstract('object', '({get foo() { return "bar"; }})') : {get foo() { return "bar"; }};
+let obj2 = global.__abstract ? __abstract('object', '({foo:{bar:"baz"}})') : {foo:{bar:"baz"}};
+if (global.__makeSimple) {
+  __makeSimple(obj2);
+}
+
+function additional1() {
+  return String(obj1.foo);
+}
+
+function additional2() {
+  return String(obj2.foo.bar);
+}
+
+inspect = function() {
+  let ret1 = additional1();
+  let ret2 = additional2();
+  return ret1 + ret2;
+}