diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9b028448..b4d2ae5e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -70,7 +70,12 @@ if(MSVC)
   set(FLAGS "/Ox")
   set(FLAGS "${FLAGS} /wd4715")
 else()
-  set(FLAGS "-O3 -std=c++11")
+  set(FLAGS "-std=c++11")
+  if(VERBOSE)
+    set(FLAGS "${FLAGS} -O1 -g")
+  else()
+    set(FLAGS "${FLAGS} -O3")
+  endif()
   if(CMAKE_CXX_COMPILER_ID STREQUAL GNU)
     set(FLAGS "${FLAGS} -Wall -Wno-comment -Wno-return-type -Wno-switch -Wno-missing-noreturn")
     if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9.0)