diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0600328..51af2f7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,9 @@
 cmake_minimum_required(VERSION 2.7)
+
+if(TARGET regex)
+  return()
+endif(TARGET regex)
+
 project(libregex)
 
 add_library(regex STATIC src/libregex.c)