diff --git a/CMakeLists.txt b/CMakeLists.txt
index f79895d044..d2f8a899c7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1553,7 +1553,7 @@ check_include_file("io.h"             HAVE_IO_H)
 check_include_file_concat_curl("libgen.h"         HAVE_LIBGEN_H)
 check_include_file("linux/tcp.h"      HAVE_LINUX_TCP_H)
 check_include_file("locale.h"         HAVE_LOCALE_H)
-check_include_file("net/if.h"         HAVE_NET_IF_H)
+check_include_file_concat_curl("net/if.h"         HAVE_NET_IF_H)  # sys/select.h (e.g. MS-DOS/Watt-32)
 check_include_file_concat_curl("netdb.h"          HAVE_NETDB_H)
 check_include_file_concat_curl("netinet/in.h"     HAVE_NETINET_IN_H)
 check_include_file("netinet/in6.h"    HAVE_NETINET_IN6_H)