diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2fc797e..cc2bc54 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,7 +5,7 @@ set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake/modules)
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -std=gnu99")
 
 include_directories(.)
-if(APPLE)
+if(UNIX)
     find_package(Argp)
     if(ARGP_FOUND)
         message(STATUS "argp found.")
@@ -15,7 +15,7 @@ if(APPLE)
 else()
     set(ARGP_INCLUDE_DIRS "")
     set(ARGP_LIBRARIES "")
-endif(APPLE)
+endif(UNIX)
 
 if(NOT RTRLIB_INCLUDE AND NOT RTRLIB_LIBRARY)
     find_package(Rtr)