diff --git a/dsk2woz.c b/dsk2woz.c
index 8856614..1d5f43f 100644
--- a/dsk2woz.c
+++ b/dsk2woz.c
@@ -210,7 +210,7 @@ static const uint32_t crc32_tab[] = {
 	@param size The size of the data to compute a CRC32 from.
 	@return The computed CRC32.
 */
-uint32_t crc32(const uint8_t *buf, size_t size) {
+static uint32_t crc32(const uint8_t *buf, size_t size) {
 	uint32_t crc = ~0;
 	size_t byte = 0;
 	while (size--) {