diff --git a/CMakeLists.txt b/CMakeLists.txt
index c602c5e2..94d9cbc2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -76,14 +76,14 @@ endif(MSVC)
 
 # C++ compiler settings
 if(MSVC)
-  set(FLAGS "/Ox")
+  set(FLAGS "/Ot")
   set(FLAGS "${FLAGS} /wd4715")
 else()
   set(FLAGS "-std=c++11")
   if(VERBOSE)
     set(FLAGS "${FLAGS} -O1 -g")
   else()
-    set(FLAGS "${FLAGS} -O3")
+    set(FLAGS "${FLAGS} -O2")
   endif()
   if(CMAKE_CXX_COMPILER_ID STREQUAL GNU)
     set(FLAGS "${FLAGS} -Wall -Wno-comment -Wno-return-type -Wno-switch -Wno-missing-noreturn")
@@ -107,9 +107,9 @@ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${FLAGS}")
 
 # C compiler settings (for the sample)
 if(MSVC)
-  set(CFLAGS "/Ox")
+  set(CFLAGS "/Ot")
 else()
-  set(CFLAGS "-O3 -std=c99")
+  set(CFLAGS "-O2 -std=c99")
 endif()
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${CFLAGS}")