--- a/mscompress.c
+++ b/mscompress.c
@@ -25,6 +25,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <string.h>
+#include <stdint.h>
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #else
@@ -156,10 +157,10 @@
   int ch, i, run, len, match, size, mask;
   char buf[17];
   struct stat st;
-  unsigned long magic1;
-  unsigned long magic2;
+  uint32_t magic1;
+  uint32_t magic2;
   unsigned short magic3;
-  unsigned long filesize;
+  uint32_t filesize;
 
   /* 28.5 kB */
   buffer = malloc (N + F + (N + 1 + N + N + 256) * sizeof (int));