diff --git a/include/pyliblexmodule.h b/include/pyliblexmodule.h
index a96b0da..7f3f48c 100644
--- a/include/pyliblexmodule.h
+++ b/include/pyliblexmodule.h
@@ -8,6 +8,9 @@ static PyObject* pyliblex_add_definition(PyObject* self, PyObject* args);
 static PyObject* pyliblex_lex(PyObject* self, PyObject* args);
 static PyObject* pyliblex_test(PyObject* self, PyObject* args);
 
+static PyObject* invalid_regex_exception;
+static PyObject* failed_lex_exception;
+
 static const char module_docstring[] = "A wrapper around a homemade lexing library, liblex.";
 static PyMethodDef module_methods[] = {
   {"init", pyliblex_init, METH_VARARGS, "Initialize a liblex library object." },
diff --git a/src/pyliblexmodule.c b/src/pyliblexmodule.c
index 0c2525a..43f51b3 100644
--- a/src/pyliblexmodule.c
+++ b/src/pyliblexmodule.c
@@ -36,8 +36,10 @@ static PyObject* pyliblex_add_definition(PyObject* self, PyObject* args){
     eval_config* config = PyCapsule_GetPointer(capsule, NULL);
     if(config){
       liblex_result result = eval_config_add(config, regex, id);
-      if(result != LIBLEX_SUCCESS){
+      if(result == LIBLEX_MALLOC){
         return_object = PyErr_NoMemory();
+      } else if(result != LIBLEX_SUCCESS){
+        PyErr_SetString(invalid_regex_exception, "Unable to construct regex.");
       } else {
         Py_INCREF(Py_None);
         return_object = Py_None;
@@ -86,8 +88,10 @@ static PyObject* pyliblex_lex(PyObject* self, PyObject* args){
 
       ll_init(&match_ll);
       result = eval_all(string, 0, config, &match_ll);
-      if(result != LIBLEX_SUCCESS){
+      if(result == LIBLEX_MALLOC){
         return_object = PyErr_NoMemory();
+      } if(result != LIBLEX_SUCCESS){
+        PyErr_SetString(failed_lex_exception, "Unable to parse text.");
       } else {
         int return_code = 0;
         PyObject* list = PyList_New(0);
@@ -115,5 +119,32 @@ static PyObject* pyliblex_test(PyObject* self, PyObject* args) {
 }
 
 PyMODINIT_FUNC PyInit_pyliblex() {
-  return PyModule_Create(&module_object);
+  invalid_regex_exception = NULL;
+  failed_lex_exception = NULL;
+  PyObject* module = NULL;
+  int clear_exceptions = 1;
+  invalid_regex_exception = PyErr_NewException("pyliblex.InvalidRegexException", NULL, NULL);
+  failed_lex_exception = PyErr_NewException("pyliblex.FailedLexException", NULL, NULL);
+
+  if(invalid_regex_exception && failed_lex_exception){
+    module = PyModule_Create(&module_object);
+    if(module) {
+      if(!(PyModule_AddObject(module, "InvalidRegexException", invalid_regex_exception) ||
+          PyModule_AddObject(module, "FailedLexException", failed_lex_exception))){
+        Py_INCREF(invalid_regex_exception);
+        Py_INCREF(failed_lex_exception);
+        clear_exceptions = 0;
+      } else {
+        Py_DECREF(module);
+        module = NULL;
+      }
+    }
+  }
+
+  if(clear_exceptions){
+    if(invalid_regex_exception) Py_DECREF(invalid_regex_exception); 
+    if(failed_lex_exception) Py_DECREF(failed_lex_exception);
+  }
+
+  return module;
 }