diff --git a/CMakeLists.txt b/CMakeLists.txt
index c77d77641..417c3dd54 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,9 +11,6 @@ PROJECT(fish)
 
 # We are C++11.
 SET(CMAKE_CXX_STANDARD 11)
-SET(CMAKE_CXX_FLAGS_DEBUG "-O0 -g")
-SET(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g")
-SET(CMAKE_CXX_FLAGS_RELEASE "-O2")
 SET(DEFAULT_BUILD_TYPE "RelWithDebInfo")
 
 IF(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)