diff --git a/Makefile b/Makefile
index a7954369..5fc1c8db 100644
--- a/Makefile
+++ b/Makefile
@@ -19,12 +19,10 @@ GST_CORE_SOURCES=$(addprefix core/,\
 				 compile.c disasm.c parse.c stl.c ids.c util.c\
 				 value.c vm.c ds.c gc.c thread.c serialize.c)
 GST_CORE_OBJECTS=$(patsubst %.c,%.o,$(GST_CORE_SOURCES))
-$(GST_CORELIB): $(GST_CORE_OBJECTS) $(GST_HEADERS)
-	ar rcs $(GST_CORELIB) $(GST_CORE_OBJECTS)
 
-##############################
-##### The example client #####
-##############################
+######################
+##### The client #####
+######################
 GST_CLIENT_SOURCES=client/main.c
 GST_CLIENT_OBJECTS=$(patsubst %.c,%.o,$(GST_CLIENT_SOURCES))
 $(GST_TARGET): $(GST_CLIENT_OBJECTS) $(GST_CORE_OBJECTS)
@@ -50,4 +48,7 @@ clean:
 	rm $(GST_CLIENT_OBJECTS) || true
 	rm vgcore.* || true
 
+test: $(GST_TARGET)
+	gsttests/basic.gst
+
 .PHONY: clean install run debug valgrind
diff --git a/client/main.c b/client/main.c
index d29e1307..08fb124c 100644
--- a/client/main.c
+++ b/client/main.c
@@ -117,6 +117,8 @@ int debug_repl(Gst *vm) {
                 break;
             if (!reader || *reader == '\0') {
                 buffer = readline(">> ");
+                if (*buffer == '\0')
+                    return 0;
                 add_history(buffer);
                 reader = buffer;
             }
diff --git a/core/compile.c b/core/compile.c
index 0d8d7340..7b07d77c 100644
--- a/core/compile.c
+++ b/core/compile.c
@@ -945,6 +945,7 @@ static SpecialFormHelper get_special(const GstValue *form) {
                     return compile_apply;
                 }
             }
+            break;
         case 'd':
             {
                 if (gst_string_length(name) == 2 &&
@@ -989,6 +990,7 @@ static SpecialFormHelper get_special(const GstValue *form) {
                     return compile_tran;
                 }
             }
+            break;
         case 'w':
             {
                 if (gst_string_length(name) == 5 &&
diff --git a/core/gc.c b/core/gc.c
index 890bbf2c..6a1c3882 100644
--- a/core/gc.c
+++ b/core/gc.c
@@ -147,6 +147,8 @@ void gst_mark(Gst *vm, GstValueUnion x, GstType type) {
                     frame = gst_mark_stackframe(vm, frame);
                 if (thread->parent)
                     gst_mark_value(vm, gst_wrap_thread(thread->parent));
+                if (thread->errorParent)
+                    gst_mark_value(vm, gst_wrap_thread(thread->errorParent));
             }
             break;
 
diff --git a/core/parse.c b/core/parse.c
index dcd80e28..e4b7eec3 100644
--- a/core/parse.c
+++ b/core/parse.c
@@ -101,6 +101,8 @@ static void parser_push(GstParser *p, ParseType type, uint8_t character) {
     switch (type) {
         case PTYPE_STRING:
             top->buf.string.state = STRING_STATE_BASE;
+            top->buf.string.buffer = gst_buffer(p->vm, 10);
+            break;
         case PTYPE_TOKEN:
             top->buf.string.buffer = gst_buffer(p->vm, 10);
             break;
@@ -458,6 +460,8 @@ static void dispatch_char(GstParser *p, uint8_t c) {
  */
 int gst_parse_cstring(GstParser *p, const char *string) {
     int bytesRead = 0;
+    if (!string)
+        return 0;
     while ((p->status == GST_PARSER_PENDING || p->status == GST_PARSER_ROOT)
             && (string[bytesRead] != '\0')) {
         dispatch_char(p, string[bytesRead++]);
@@ -468,6 +472,8 @@ int gst_parse_cstring(GstParser *p, const char *string) {
 /* Parse a gst string */
 int gst_parse_string(GstParser *p, const uint8_t *string) {
     uint32_t i;
+    if (!string)
+        return 0;
     for (i = 0; i < gst_string_length(string); ++i) {
         if (p->status != GST_PARSER_PENDING && p->status != GST_PARSER_ROOT) break;
         dispatch_char(p, string[i]);
diff --git a/core/serialize.c b/core/serialize.c
index f27224e4..1a57431e 100644
--- a/core/serialize.c
+++ b/core/serialize.c
@@ -38,7 +38,7 @@
  * Byte 207: Buffer  - [u32 capacity][u32 length]*[u8... characters]
  * Byte 208: Array   - [u32 length]*[value... elements]
  * Byte 209: Tuple   - [u32 length]*[value... elements]
- * Byte 210: Thread  - [value parent][u8 state][u32 frames]*[[value callee][value env]
+ * Byte 210: Thread  - [value parent][value errorParent][u8 state][u32 frames]*[[value callee][value env]
  *  [u32 pcoffset][u32 ret][u32 args][u32 size]*[value ...stack]]
  * Byte 211: Table   - [u32 length]*2*[value... kvs]
  * Byte 212: FuncDef - [u32 locals][u32 arity][u32 flags][u32 literallen]*[value...
@@ -249,7 +249,16 @@ static const char *gst_deserialize_impl(
                 } else if (ret.type == GST_THREAD) {
                     t->parent = ret.data.thread;
                 } else {
-                    return "expected thread parent to thread";
+                    return "expected thread parent to be thread";
+                }
+                err = gst_deserialize_impl(vm, data, end, &data, visited, &ret);
+                if (err != NULL) return err;
+                if (ret.type == GST_NIL) {
+                    t->errorParent = NULL;
+                } else if (ret.type == GST_THREAD) {
+                    t->errorParent = ret.data.thread;
+                } else {
+                    return "expected thread error parent to be thread";
                 }
                 deser_assert(data < end, UEB);
                 statusbyte = *data++;
@@ -520,10 +529,10 @@ const char *gst_serialize_impl(
     }
 
     /* Check tuples and structs before other reference types.
-     * They ae immutable, and thus cannot be referenced by other values
+     * They are immutable, and thus cannot be referenced by other values
      * until they are fully constructed. This creates some strange behavior
      * if they are treated like other reference types because they cannot
-     * be added to the visited table before recusring into serializing their
+     * be added to the visited table before recursing into serializing their
      * arguments */
     if (x.type == GST_STRUCT || x.type == GST_TUPLE) {
         if (x.type == GST_STRUCT) {
@@ -632,6 +641,11 @@ const char *gst_serialize_impl(
                     err = gst_serialize_impl(vm, buffer, visited, nextId, gst_wrap_thread(t->parent));
                 else
                     err = gst_serialize_impl(vm, buffer, visited, nextId, gst_wrap_nil());
+                if (t->errorParent)
+                    err = gst_serialize_impl(vm, buffer, visited, nextId,
+							gst_wrap_thread(t->errorParent));
+                else
+                    err = gst_serialize_impl(vm, buffer, visited, nextId, gst_wrap_nil());
                 if (err != NULL) return err;
                 /* Write the status byte */
                 write_byte(t->status);
diff --git a/core/stl.c b/core/stl.c
index 58b3543e..d8b5b2f7 100644
--- a/core/stl.c
+++ b/core/stl.c
@@ -446,9 +446,21 @@ int gst_stl_string(Gst *vm) {
 int gst_stl_thread(Gst *vm) {
     GstThread *t;
     GstValue callee = gst_arg(vm, 0);
+    GstValue parent = gst_arg(vm, 1);
+    GstValue errorParent = gst_arg(vm, 2);
+    t = gst_thread(vm, callee, 10);
     if (callee.type != GST_FUNCTION && callee.type != GST_CFUNCTION)
         gst_c_throwc(vm, "expected function in thread constructor");
-    t = gst_thread(vm, callee, 10);
+    if (parent.type == GST_THREAD) {
+        t->parent = parent.data.thread;    
+    } else if (parent.type != GST_NIL) {
+        gst_c_throwc(vm, "expected thread/nil as parent");
+    }
+    if (errorParent.type == GST_THREAD) {
+        t->errorParent = errorParent.data.thread;    
+    } else if (errorParent.type != GST_NIL) {
+        gst_c_throwc(vm, "expected thread/nil as error parent");
+    }
     t->parent = vm->thread;
     gst_c_return(vm, gst_wrap_thread(t));
 }
@@ -669,12 +681,13 @@ int gst_stl_namespace_set(Gst *vm) {
 
 /* Get the table or struct associated with a given namespace */
 int gst_stl_namespace_get(Gst *vm) {
-    GstValue name = gst_arg(vm, 0);
-    GstValue check;
-    if (name.type != GST_STRING)
-        gst_c_throwc(vm, "expected string");
-    check = gst_table_get(vm->modules, name);
-    gst_c_return(vm, check);
+    return gst_callc(vm, gst_stl_get, 2, gst_wrap_table(vm->modules), gst_arg(vm, 0));
+    /*GstValue name = gst_arg(vm, 0);*/
+    /*GstValue check;*/
+    /*if (name.type != GST_STRING)*/
+        /*gst_c_throwc(vm, "expected string");*/
+    /*check = gst_table_get(vm->modules, name);*/
+    /*gst_c_return(vm, check);*/
 }
 
 /***/
@@ -796,7 +809,7 @@ int gst_stl_close(Gst *vm) {
 }
 
 /* Functions in the io module */
-static const GstModuleItem const io_dat[] = {
+static const GstModuleItem io_dat[] = {
     {"open", gst_stl_open},
     {"slurp", gst_stl_slurp},
     {"read", gst_stl_read},
@@ -914,7 +927,7 @@ int gst_stl_debugp(Gst *vm) {
 /* Bootstraping */
 /****/
 
-static const GstModuleItem const std_module[] = {
+static const GstModuleItem std_module[] = {
     /* Arithmetic */
     {"+", gst_stl_add},
     {"*", gst_stl_mul},
diff --git a/core/thread.c b/core/thread.c
index 1d942fa0..2cec03f1 100644
--- a/core/thread.c
+++ b/core/thread.c
@@ -42,6 +42,7 @@ GstThread *gst_thread(Gst *vm, GstValue callee, uint32_t capacity) {
     gst_frame_callee(stack) = callee;
     gst_thread_endframe(vm, thread);
     thread->parent = NULL; /* Need to set parent manually */
+    thread->errorParent = NULL;
     return thread;
 }
 
diff --git a/core/util.c b/core/util.c
index 2a4b0b0a..c05523d6 100644
--- a/core/util.c
+++ b/core/util.c
@@ -237,3 +237,18 @@ GstInteger gst_endrange(GstInteger raw, uint32_t len) {
         return len + raw + 1;
     return raw;
 }
+
+int gst_callc(Gst *vm, GstCFunction fn, int numargs, ...) {
+    int result, i;
+    va_list args;
+    GstValue *stack;
+    va_start(args, numargs);
+    stack = gst_thread_beginframe(vm, vm->thread, gst_wrap_cfunction(fn), numargs);
+    for (i = 0; i < numargs; ++i) {
+        stack[i] = va_arg(args, GstValue);
+    }
+    va_end(args);
+    result = fn(vm);
+    gst_thread_popframe(vm, vm->thread);
+    return result;
+}
diff --git a/core/vm.c b/core/vm.c
index 291ed755..b58387f0 100644
--- a/core/vm.c
+++ b/core/vm.c
@@ -394,9 +394,9 @@ int gst_continue(Gst *vm) {
         /* Handle errors from c functions and vm opcodes */
         vm_error:
             vm->thread->status = GST_THREAD_ERROR;
-            if (vm->thread->parent == NULL)
+            if (vm->thread->errorParent == NULL)
                 return GST_RETURN_ERROR;
-            vm->thread = vm->thread->parent;
+            vm->thread = vm->thread->errorParent;
             stack = vm->thread->data + vm->thread->count;
             stack[gst_frame_ret(stack)] = vm->ret;
             pc = gst_frame_pc(stack);
diff --git a/gsttests/basic.gst b/gsttests/basic.gst
index 96e699f9..291b2db4 100644
--- a/gsttests/basic.gst
+++ b/gsttests/basic.gst
@@ -1,11 +1,8 @@
-# Define assert
+(do
 (: assert (fn [x e] (if x x (do (print e) (exit 1)))))
-
-# Basic Math
-(assert (= 10 (+ 1 2 3 4), "addition")
-(assert (= -8 (- 1 2 3 4), "subtraction")
-(assert (= 24 (* 1 2 3 4), "multiplication")
-(assert (= 0.1 (/ 1 10), "division")
-
-# All good
+(assert (= 10 (+ 1 2 3 4)) "addition")
+(assert (= -8 (- 1 2 3 4)) "subtraction")
+(assert (= 24 (* 1 2 3 4)) "multiplication")
+(assert (= 0.1 (/ 1.0 10)) "division")
 (exit 0)
+)
diff --git a/include/gst/gst.h b/include/gst/gst.h
index 51fae5e4..982d0e5c 100644
--- a/include/gst/gst.h
+++ b/include/gst/gst.h
@@ -24,6 +24,7 @@
 #define GST_H_defined
 
 #include <stdint.h>
+#include <stdarg.h>
 
 /* String utils */
 #define gst_string_raw(s) ((uint32_t *)(s) - 2)
@@ -206,6 +207,7 @@ struct GstThread {
     uint32_t capacity;
     GstValue *data;
     GstThread *parent;
+    GstThread *errorParent;
     enum {
         GST_THREAD_PENDING = 0,
         GST_THREAD_ALIVE,
@@ -490,10 +492,13 @@ uint32_t gst_count_args(Gst *vm);
 /* C Api */
 /****/
 
-void gst_module(Gst *vm, const char *packagename, const GstModuleItem *mod);
-void gst_module_mutable(Gst *vm, const char *packagename, const GstModuleItem *mod);
+void gst_module(Gst *vm, const char *name, const GstModuleItem *mod);
+void gst_module_mutable(Gst *vm, const char *name, const GstModuleItem *mod);
+void gst_module_put(Gst *vm, const char *packagename, const char *name, GstValue x);
 GstValue gst_module_get(Gst *vm, const char *packagename);
-void gst_module_put(Gst *vm, const char *packagename, const char *name, GstValue v);
+void gst_register_put(Gst *vm, const char *packagename, GstValue mod);
+GstValue gst_register_get(Gst *vm, const char *name);
+int gst_callc(Gst *vm, GstCFunction fn, int numargs, ...);
 
 /* Wrap data in GstValue */
 GstValue gst_wrap_nil();