diff --git a/crc32.c b/crc32.c
index fa2d770..6e0ebb1 100644
--- a/crc32.c
+++ b/crc32.c
@@ -1,9 +1,9 @@
 enum { CRC_TABLE_SIZE = 0x100 };
 
-ulong
-crc_reflect(ulong input)
+uint32_t
+crc_reflect(uint32_t input)
 {
-	ulong reflected = 0;
+	uint32_t reflected = 0;
 	for (int i = 0; i < 4 * 8; i++) {
 		reflected <<= 1;
 		reflected |= input & 1;
@@ -13,10 +13,10 @@ crc_reflect(ulong input)
 }
 
 void
-crc_fill_table(ulong *table, int big, ulong polynomial)
+crc_fill_table(uint32_t *table, int big, uint32_t polynomial)
 {
-	ulong lsb = (big) ? 1 << 31 : 1; /* least significant bit */
-	ulong poly = (big) ? polynomial : crc_reflect(polynomial);
+	uint32_t lsb = (big) ? 1 << 31 : 1; /* least significant bit */
+	uint32_t poly = (big) ? polynomial : crc_reflect(polynomial);
 
 	for (int c = 0; c < CRC_TABLE_SIZE; c++, table++) {
 		*table = (big) ? c << 24 : c;
@@ -33,15 +33,15 @@ crc_fill_table(ulong *table, int big, ulong polynomial)
 }
 
 void
-crc_be_cycle(ulong *table, ulong *remainder, char c)
+crc_be_cycle(uint32_t *table, uint32_t *remainder, char c)
 {
-	ulong byte = table[(((*remainder) >> 24) ^ c) & 0xff];
+	uint32_t byte = table[(((*remainder) >> 24) ^ c) & 0xff];
 	*remainder = (((*remainder) << 8) ^ byte) & 0xFFFFFFFF;
 }
 
 void
-crc_le_cycle(ulong *table, ulong *remainder, char c)
+crc_le_cycle(uint32_t *table, uint32_t *remainder, char c)
 {
-	ulong byte = table[((*remainder) ^ c) & 0xFF];
+	uint32_t byte = table[((*remainder) ^ c) & 0xFF];
 	*remainder = ((*remainder) >> 8) ^ byte;
 }
diff --git a/main.c b/main.c
index 9c10dc4..6ca39b4 100644
--- a/main.c
+++ b/main.c
@@ -1,7 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
-
-typedef unsigned long ulong;
+#include <stdint.h>
 
 #include "crc32.c"
 #include "args.c"
@@ -19,9 +18,9 @@ struct string_node_s {
 
 static string_node *input_node = NULL;
 
-static ulong starting = 0xFFFFFFFF;
+static uint32_t starting = 0xFFFFFFFF;
 static char big_endian = 0;
-static ulong polynomial = 0x04C11DB7;
+static uint32_t polynomial = 0x04C11DB7;
 static char print_binary = 0;
 static char xor_output = 1;
 static char reflect_output = 0;
@@ -118,13 +117,13 @@ open_stream(char *filename)
 }
 
 
-static ulong
+static uint32_t
 cycle_file(FILE *stream)
 {
-	ulong remainder = starting;
-	void (*cycle)(ulong*, ulong*, char) =
+	uint32_t remainder = starting;
+	void (*cycle)(uint32_t*, uint32_t*, char) =
 	    (big_endian) ? crc_be_cycle : crc_le_cycle;
-	ulong table[CRC_TABLE_SIZE];
+	uint32_t table[CRC_TABLE_SIZE];
 
 	crc_fill_table(table, big_endian, polynomial);
 	do {
@@ -146,7 +145,7 @@ cycle_file(FILE *stream)
 }
 
 static void
-print_crc(ulong remainder)
+print_crc(uint32_t remainder)
 {
 	if (print_binary)
 		fwrite(&remainder, sizeof(remainder), 1, stdout);