diff --git a/libzpaq/libzpaq.h b/libzpaq/libzpaq.h
index e6109af..93387da 100644
--- a/libzpaq/libzpaq.h
+++ b/libzpaq/libzpaq.h
@@ -449,7 +449,7 @@ void compress(Reader* in, Writer* out, int level);
 #define unlikely(x)	__builtin_expect(!!(x), 0)
 #define __maybe_unused	__attribute__((unused))
 
-typedef long long int i64;
+typedef int64_t i64;
 
 struct bufRead: public libzpaq::Reader {
 	uchar *s_buf;
diff --git a/lrzip_private.h b/lrzip_private.h
index 2bbd3c9..d9e6db9 100644
--- a/lrzip_private.h
+++ b/lrzip_private.h
@@ -144,7 +144,7 @@ extern int errno;
 # define ffsll __builtin_ffsll
 #endif
 
-typedef long long int i64;
+typedef int64_t i64;
 typedef uint32_t u32;
 
 typedef struct rzip_control rzip_control;