diff --git a/CMakeLists.txt b/CMakeLists.txt
index 29f5d7ed..f533f165 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -210,7 +210,12 @@ CHECK_INCLUDE_FILES (malloc.h              HAVE_MALLOC_H)
 CHECK_INCLUDE_FILES (memory.h              HAVE_MEMORY_H)
 CHECK_INCLUDE_FILES (netdb.h               HAVE_NETDB_H)
 CHECK_INCLUDE_FILES (netinet/in.h          HAVE_NETINET_IN_H)
-CHECK_INCLUDE_FILES (net/if.h              HAVE_NET_IF_H)
+# On old MacOS SDK versions, you must include sys/socket.h before net/if.h
+IF (HAVE_SYS_SOCKET_H)
+  CHECK_INCLUDE_FILES ("sys/socket.h;net/if.h"  HAVE_NET_IF_H)
+ELSE ()
+  CHECK_INCLUDE_FILES (net/if.h                 HAVE_NET_IF_H)
+ENDIF ()
 CHECK_INCLUDE_FILES (signal.h              HAVE_SIGNAL_H)
 CHECK_INCLUDE_FILES (socket.h              HAVE_SOCKET_H)
 CHECK_INCLUDE_FILES (stdbool.h             HAVE_STDBOOL_H)