diff --git a/PLATFORMS b/PLATFORMS
index 34787f29..4f11c515 100644
--- a/PLATFORMS
+++ b/PLATFORMS
@@ -7,6 +7,7 @@ tcpdump compiles and works on at least the following platforms:
 
 * AIX
 * FreeBSD
+* HP-UX 11i
 * Linux (any) with glibc (usually just works)
 * Linux (any) with musl libc (sometimes fails to compile, please report any bugs)
 * Mac OS X / macOS