diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5ff7ea555..21f241532 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -212,19 +212,19 @@ endif()
 if(CMAKE_BUILD_TYPE MATCHES Debug OR CMAKE_BUILD_TYPE MATCHES RelWithDebInfo)
   message(STATUS "Configuring debug mode flags")
   set(ENABLE_ASSERTIONS ON)
-  if(NOT CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-inline -fno-omit-frame-pointer")
-    if(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
-      if (CMAKE_BUILD_TYPE MATCHES Debug)
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Og -ggdb")
-      else()
-        # Don't override the -O parameter for RelWithDebInfo, we want an optimized build
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ggdb")
-      endif()
-    endif()
-  endif()
 endif()
 
+if(NOT CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
+  set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -fno-inline -fno-omit-frame-pointer")
+  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -fno-inline -fno-omit-frame-pointer")
+endif()
+
+if(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
+  set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -ggdb")
+  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -Og -ggdb")
+endif()
+
+
 if(CMAKE_BUILD_TYPE MATCHES Release OR CMAKE_BUILD_TYPE MATCHES MinRelSize OR CMAKE_BUILD_TYPE MATCHES RelWithDebInfo)
   message(STATUS "Configuring release mode optimizations")
   # Check if LTO is available
@@ -304,10 +304,11 @@ if (ENABLE_COVERAGE)
   if (NOT CMAKE_BUILD_TYPE MATCHES "Debug")
     message(ERROR "ENABLE_COVERAGE=ON only make sense with a Debug build")
   endif()
-  message(INFO "Enabling coverage")
+  message(STATUS "Enabling coverage")
   set(MAYBE_COVERAGE_LIBRARIES "-lgcov")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ftest-coverage -fprofile-arcs")
+  set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -O0 -ftest-coverage -fprofile-arcs")
 endif()
+
 if (ENABLE_SANITIZER)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address")
   set(OSRM_CXXFLAGS "${OSRM_CXXFLAGS} -fsanitize=address")