diff --git a/development/cmake/CMakeLists.txt b/development/cmake/CMakeLists.txt
index 7489b8cf37..1fdc20f6b3 100644
--- a/development/cmake/CMakeLists.txt
+++ b/development/cmake/CMakeLists.txt
@@ -181,7 +181,7 @@ if(NOT MSVC)
 		set(LYX_CXX_FLAGS "${LYX_CXX_FLAGS} -D_GLIBCPP_CONCEPT_CHECKS")
 	endif()
 	set(CMAKE_CXX_FLAGS          "${LYX_CXX_FLAGS} -fno-strict-aliasing " CACHE TYPE STRING FORCE)
-	set(CMAKE_CXX_FLAGS_DEBUG    "${LYX_CXX_FLAGS} -fno-strict-aliasing -O  -D_DEBUG" CACHE TYPE STRING FORCE)
+	set(CMAKE_CXX_FLAGS_DEBUG    "${LYX_CXX_FLAGS} -fno-strict-aliasing -O0 -g -D_DEBUG" CACHE TYPE STRING FORCE)
 	if(MINGW)
 		set(CMAKE_CXX_FLAGS_RELEASE  "${LYX_CXX_FLAGS} -O2 -DNDEBUG" CACHE TYPE STRING FORCE)
 	else()