diff --git a/pixie/ffi-infer.pxi b/pixie/ffi-infer.pxi
index b2db256b..5e3b086f 100644
--- a/pixie/ffi-infer.pxi
+++ b/pixie/ffi-infer.pxi
@@ -98,7 +98,8 @@ return 0;
 (defmethod edn-to-ctype :pointer
   [{:keys [of-type] :as ptr} in-struct?]
   (cond
-   (and (= of-type {:signed? true :size 1 :type :int})
+   (and (= (:size of-type) 1)
+        (= (:type of-type) :int)
         (not in-struct?)) 'pixie.stdlib/CCharP
    (= (:type of-type) :function) (callback-type of-type in-struct?)
    :else 'pixie.stdlib/CVoidP))
diff --git a/pixie/vm/libs/ffi.py b/pixie/vm/libs/ffi.py
index 1a30a535..0d346472 100644
--- a/pixie/vm/libs/ffi.py
+++ b/pixie/vm/libs/ffi.py
@@ -394,8 +394,9 @@ def ffi_set_value(self, ptr, val):
             vpnt = rffi.cast(rffi.VOIDPP, ptr)
             vpnt[0] = rffi.cast(rffi.VOIDP, val.raw_data())
         else:
-            print val
-            affirm(False, u"Cannot encode this type")
+            frm_name = rt.name(rt.str(val.type()))
+            to_name = rt.name(rt.str(self))
+            affirm(False, u"Cannot encode " + frm_name + u" as " + to_name)
 
 
     def ffi_size(self):
@@ -445,7 +446,13 @@ def ffi_get_value(self, ptr):
 
     def ffi_set_value(self, ptr, val):
         pnt = rffi.cast(rffi.VOIDPP, ptr)
-        if isinstance(val, Buffer):
+        if isinstance(val, String):
+            pnt = rffi.cast(rffi.CCHARPP, ptr)
+            utf8 = unicode_to_utf8(rt.name(val))
+            raw = rffi.str2charp(utf8)
+            pnt[0] = raw
+            return CCharPToken(raw)
+        elif isinstance(val, Buffer):
             pnt[0] = val.buffer()
         elif isinstance(val, VoidP):
             pnt[0] = val.raw_data()
@@ -454,8 +461,10 @@ def ffi_set_value(self, ptr, val):
         elif isinstance(val, CStruct):
             pnt[0] = rffi.cast(rffi.VOIDP, val.raw_data())
         else:
-            print val
-            affirm(False, u"Cannot encode this type")
+            frm_name = rt.name(rt.str(val.type()))
+            to_name = rt.name(rt.str(self))
+            affirm(False, u"Cannot encode " + frm_name + u" as " + to_name)
+
 
     def ffi_size(self):
         return rffi.sizeof(rffi.VOIDP)
diff --git a/pixie/vm/object.py b/pixie/vm/object.py
index 2abf674e..32bdd199 100644
--- a/pixie/vm/object.py
+++ b/pixie/vm/object.py
@@ -151,6 +151,16 @@ def runtime_error(msg):
     import pixie.vm.rt as rt
     raise WrappedException(RuntimeException(rt.wrap(msg)))
 
+def safe_invoke(f, args):
+    try:
+        f.invoke(args)
+    except Exception as ex:
+        if isinstance(ex, WrappedException):
+            print "UNSAFE EXCEPTION", ex._ex.__repr__()
+        else:
+            print "UNSAFE EXCEPTION", ex
+    return None
+
 class ErrorInfo(Object):
     _type = Type(u"pixie.stdlib.ErrorInfo")
     def type(self):
diff --git a/pixie/vm/threads.py b/pixie/vm/threads.py
index d34b47b8..5140608b 100644
--- a/pixie/vm/threads.py
+++ b/pixie/vm/threads.py
@@ -1,4 +1,4 @@
-from pixie.vm.object import Object, Type
+from pixie.vm.object import Object, Type, safe_invoke
 from pixie.vm.primitives import true
 import rpython.rlib.rthread as rthread
 from pixie.vm.primitives import nil
@@ -42,7 +42,7 @@ def bootstrap():
     rthread.gc_thread_start()
     fn = bootstrapper.fn()
     bootstrapper.release()
-    fn.invoke([])
+    safe_invoke(fn, [])
     rthread.gc_thread_die()
 
 bootstrapper = Bootstrapper()