diff --git a/nilmdb/server/rocket.c b/nilmdb/server/rocket.c
index 98f4157..f8bcc19 100644
--- a/nilmdb/server/rocket.c
+++ b/nilmdb/server/rocket.c
@@ -168,7 +168,7 @@ static int Rocket_init(Rocket *self, PyObject *args, PyObject *kwds)
 	if (!layout)
 		return -1;
 	if (path) {
-                if (strlen(path) != pathlen) {
+                if (strlen(path) != (size_t)pathlen) {
                         PyErr_SetString(PyExc_ValueError, "path must not "
                                         "contain NUL characters");
                         return -1;
@@ -477,7 +477,7 @@ static PyObject *Rocket_append_binary(Rocket *self, PyObject *args)
         }
 
         /* Write binary data */
-        if (fwrite(data, self->binary_size, rows, self->file) != rows) {
+        if (fwrite(data, self->binary_size, rows, self->file) != (size_t)rows) {
                 PyErr_SetFromErrno(PyExc_OSError);
                 return NULL;
         }
@@ -628,7 +628,7 @@ static PyObject *Rocket_extract_binary(Rocket *self, PyObject *args)
 
         /* Data in the file is already in the desired little-endian
            binary format, so just read it directly. */
-        if (fread(str, self->binary_size, count, self->file) != count) {
+        if (fread(str, self->binary_size, count, self->file) != (size_t)count) {
                 free(str);
                 PyErr_SetFromErrno(PyExc_OSError);
                 return NULL;