diff --git a/bson/_cbsonmodule.c b/bson/_cbsonmodule.c
index 3e9d5ecc26..51ad13a008 100644
--- a/bson/_cbsonmodule.c
+++ b/bson/_cbsonmodule.c
@@ -207,7 +207,7 @@ static PyObject* _test_long_long_to_str(PyObject* self, PyObject* args) {
  *
  * Returns a new ref */
 static PyObject* _error(char* name) {
-    PyObject* error;
+    PyObject* error = NULL;
     PyObject* errors = PyImport_ImportModule("bson.errors");
     if (!errors) {
         return NULL;
@@ -279,7 +279,7 @@ static PyObject* datetime_from_millis(long long millis) {
      * micros = diff * 1000                       111000
      * Resulting in datetime(1, 1, 1, 1, 1, 1, 111000) -- the expected result
      */
-    PyObject* datetime;
+    PyObject* datetime = NULL;
     int diff = (int)(((millis % 1000) + 1000) % 1000);
     int microseconds = diff * 1000;
     Time64_T seconds = (millis - diff) / 1000;
@@ -294,7 +294,7 @@ static PyObject* datetime_from_millis(long long millis) {
                                           timeinfo.tm_sec,
                                           microseconds);
     if(!datetime) {
-        PyObject *etype, *evalue, *etrace;
+        PyObject *etype = NULL, *evalue = NULL, *etrace = NULL;
 
         /*
         * Calling _error clears the error state, so fetch it first.
@@ -350,8 +350,8 @@ static PyObject* datetime_ms_from_millis(PyObject* self, long long millis){
         return NULL;
     }
 
-    PyObject* dt;
-    PyObject* ll_millis;
+    PyObject* dt = NULL;
+    PyObject* ll_millis = NULL;
 
     if (!(ll_millis = PyLong_FromLongLong(millis))){
         return NULL;
@@ -1790,7 +1790,7 @@ static PyObject* _cbson_dict_to_bson(PyObject* self, PyObject* args) {
     PyObject* result;
     unsigned char check_keys;
     unsigned char top_level = 1;
-    PyObject* options_obj;
+    PyObject* options_obj = NULL;
     codec_options_t options;
     buffer_t buffer;
     PyObject* raw_bson_document_bytes_obj;
@@ -2512,8 +2512,8 @@ static PyObject* get_value(PyObject* self, PyObject* name, const char* buffer,
      * Wrap any non-InvalidBSON errors in InvalidBSON.
      */
     if (PyErr_Occurred()) {
-        PyObject *etype, *evalue, *etrace;
-        PyObject *InvalidBSON;
+        PyObject *etype = NULL, *evalue = NULL, *etrace = NULL;
+        PyObject *InvalidBSON = NULL;
 
         /*
          * Calling _error clears the error state, so fetch it first.
@@ -2585,8 +2585,8 @@ static int _element_to_dict(PyObject* self, const char* string,
     if (!*name) {
         /* If NULL is returned then wrap the UnicodeDecodeError
            in an InvalidBSON error */
-        PyObject *etype, *evalue, *etrace;
-        PyObject *InvalidBSON;
+        PyObject *etype = NULL, *evalue = NULL, *etrace = NULL;
+        PyObject *InvalidBSON = NULL;
 
         PyErr_Fetch(&etype, &evalue, &etrace);
         if (PyErr_GivenExceptionMatches(etype, PyExc_Exception)) {
@@ -2620,7 +2620,7 @@ static PyObject* _cbson_element_to_dict(PyObject* self, PyObject* args) {
     /* TODO: Support buffer protocol */
     char* string;
     PyObject* bson;
-    PyObject* options_obj;
+    PyObject* options_obj = NULL;
     codec_options_t options;
     unsigned position;
     unsigned max;
@@ -2732,7 +2732,7 @@ static PyObject* _cbson_bson_to_dict(PyObject* self, PyObject* args) {
     int32_t size;
     Py_ssize_t total_size;
     const char* string;
-    PyObject* bson;
+    PyObject* bson = NULL;
     codec_options_t options;
     PyObject* result = NULL;
     PyObject* options_obj;
diff --git a/pymongo/_cmessagemodule.c b/pymongo/_cmessagemodule.c
index f95b949380..b5adbeec32 100644
--- a/pymongo/_cmessagemodule.c
+++ b/pymongo/_cmessagemodule.c
@@ -45,7 +45,7 @@ struct module_state {
  *
  * Returns a new ref */
 static PyObject* _error(char* name) {
-    PyObject* error;
+    PyObject* error = NULL;
     PyObject* errors = PyImport_ImportModule("pymongo.errors");
     if (!errors) {
         return NULL;
@@ -75,9 +75,9 @@ static PyObject* _cbson_query_message(PyObject* self, PyObject* args) {
     int begin, cur_size, max_size = 0;
     int num_to_skip;
     int num_to_return;
-    PyObject* query;
-    PyObject* field_selector;
-    PyObject* options_obj;
+    PyObject* query = NULL;
+    PyObject* field_selector = NULL;
+    PyObject* options_obj = NULL;
     codec_options_t options;
     buffer_t buffer = NULL;
     int length_location, message_length;
@@ -221,12 +221,12 @@ static PyObject* _cbson_op_msg(PyObject* self, PyObject* args) {
     /* NOTE just using a random number as the request_id */
     int request_id = rand();
     unsigned int flags;
-    PyObject* command;
+    PyObject* command = NULL;
     char* identifier = NULL;
     Py_ssize_t identifier_length = 0;
-    PyObject* docs;
-    PyObject* doc;
-    PyObject* options_obj;
+    PyObject* docs = NULL;
+    PyObject* doc = NULL;
+    PyObject* options_obj = NULL;
     codec_options_t options;
     buffer_t buffer = NULL;
     int length_location, message_length;
@@ -535,12 +535,12 @@ static PyObject*
 _cbson_encode_batched_op_msg(PyObject* self, PyObject* args) {
     unsigned char op;
     unsigned char ack;
-    PyObject* command;
-    PyObject* docs;
+    PyObject* command = NULL;
+    PyObject* docs = NULL;
     PyObject* ctx = NULL;
     PyObject* to_publish = NULL;
     PyObject* result = NULL;
-    PyObject* options_obj;
+    PyObject* options_obj = NULL;
     codec_options_t options;
     buffer_t buffer;
     struct module_state *state = GETSTATE(self);
@@ -592,12 +592,12 @@ _cbson_batched_op_msg(PyObject* self, PyObject* args) {
     unsigned char ack;
     int request_id;
     int position;
-    PyObject* command;
-    PyObject* docs;
+    PyObject* command = NULL;
+    PyObject* docs = NULL;
     PyObject* ctx = NULL;
     PyObject* to_publish = NULL;
     PyObject* result = NULL;
-    PyObject* options_obj;
+    PyObject* options_obj = NULL;
     codec_options_t options;
     buffer_t buffer;
     struct module_state *state = GETSTATE(self);
@@ -868,12 +868,12 @@ _cbson_encode_batched_write_command(PyObject* self, PyObject* args) {
     char *ns = NULL;
     unsigned char op;
     Py_ssize_t ns_len;
-    PyObject* command;
-    PyObject* docs;
+    PyObject* command = NULL;
+    PyObject* docs = NULL;
     PyObject* ctx = NULL;
     PyObject* to_publish = NULL;
     PyObject* result = NULL;
-    PyObject* options_obj;
+    PyObject* options_obj = NULL;
     codec_options_t options;
     buffer_t buffer;
     struct module_state *state = GETSTATE(self);