diff --git a/CMakeLists.txt b/CMakeLists.txt
index ba0b3d7a..e29949a8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -30,7 +30,7 @@ else()
     message(STATUS "Build type ${CMAKE_BUILD_TYPE}")
 endif()
 
-if(CMAKE_BUILD_TYPE MATCHES RELEASE|RELWITHDEBINFO)
+if(CMAKE_BUILD_TYPE MATCHES RELEASE|RELWITHDEBINFO|MINSIZEREL)
     set(RELEASE_BUILD TRUE)
 else()
     set(RELEASE_BUILD FALSE)
@@ -218,8 +218,13 @@ else()
     endif()
 
     if(OPTIMISE)
-        set(OPT_C_FLAG "-O3")
-        set(OPT_CXX_FLAG "-O2")
+        if (NOT CMAKE_BUILD_TYPE MATCHES MINSIZEREL)
+            set(OPT_C_FLAG "-O3")
+            set(OPT_CXX_FLAG "-O2")
+        else ()
+            set(OPT_C_FLAG "-Os")
+            set(OPT_CXX_FLAG "-Os")
+        endif ()
     else()
         set(OPT_C_FLAG "-O0")
         set(OPT_CXX_FLAG "-O0")