diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index 4ae789b..1184197 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -144,7 +144,7 @@ static int debug_hw_points;
    ptrace calls to the kernel, i.e. avoid asking the kernel to write
    to the debug registers with unchanged values.  */
 
-typedef unsigned LONGEST dr_changed_t;
+typedef ULONGEST dr_changed_t;
 
 /* Set each of the lower M bits of X to 1; assert X is wide enough.  */