diff --git a/configure.ac b/configure.ac
index b10d819a..bc8592d0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -26,24 +26,31 @@ AC_USE_SYSTEM_EXTENSIONS
 case "$target_os" in
 linux*|gnu*)
    my_htop_platform=linux
+   AC_DEFINE([HTOP_LINUX], [], [Building for Linux])
    ;;
 freebsd*|kfreebsd*)
    my_htop_platform=freebsd
+   AC_DEFINE([HTOP_FREEBSD], [], [Building for FreeBSD])
    ;;
 openbsd*)
    my_htop_platform=openbsd
+   AC_DEFINE([HTOP_OPENBSD], [], [Building for OpenBSD])
    ;;
 dragonfly*)
    my_htop_platform=dragonflybsd
+   AC_DEFINE([HTOP_DRAGONFLYBSD], [], [Building for DragonFlyBSD])
    ;;
 darwin*)
    my_htop_platform=darwin
+   AC_DEFINE([HTOP_DARWIN], [], [Building for Darwin])
    ;;
 solaris*)
    my_htop_platform=solaris
+   AC_DEFINE([HTOP_SOLARIS], [], [Building for Solaris])
    ;;
 *)
    my_htop_platform=unsupported
+   AC_DEFINE([HTOP_UNSUPPORTED], [], [Building for an unsupported platform])
    ;;
 esac