diff --git a/src/crc32.c b/src/crc32.c
index bb908411..cdad7bce 100644
--- a/src/crc32.c
+++ b/src/crc32.c
@@ -70,11 +70,9 @@ static const unsigned int crc_c[256] = {
 };
 
 
-unsigned long
-generate_crc32c(char *buffer, size_t length)
-{
-  unsigned int i;
-  unsigned long crc32 = ~0L;
+uint32_t generate_crc32c(char *buffer, size_t length) {
+  size_t i;
+  uint32_t crc32 = ~0L;
 
   for (i = 0; i < length; i++){
       CRC32C(crc32, (unsigned char)buffer[i]);
diff --git a/src/crc32.h b/src/crc32.h
index f89ab0eb..77ebd98d 100644
--- a/src/crc32.h
+++ b/src/crc32.h
@@ -2,7 +2,8 @@
 #define __crc32cr_table_h__
 
 #include <sys/types.h>
+#include <stdint.h>
 
-unsigned long generate_crc32c(char *string, size_t length);
+uint32_t generate_crc32c(char *string, size_t length);
 
 #endif