diff --git a/CMakeLists.txt b/CMakeLists.txt
index 80ad00c9..f91cf57a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -62,7 +62,7 @@ if(REALTIME)
             if(ALSA_FOUND)
                 include_directories(${ALSA_INCLUDE_DIRS})
                 link_libraries(${ALSA_LIBRARIES})
-                add_definitions(__LINUX_ALSA__)
+                add_definitions(-D__LINUX_ALSA__)
             endif()
         endif()
     elseif(${CMAKE_SYSTEM_NAME} STREQUAL Darwin)