diff --git a/cmake/cross-mingw32/debug/CMakeLists.txt b/cmake/cross-mingw32/debug/CMakeLists.txt
index 15616426..4ed85291 100644
--- a/cmake/cross-mingw32/debug/CMakeLists.txt
+++ b/cmake/cross-mingw32/debug/CMakeLists.txt
@@ -1,3 +1,4 @@
 project("fceux: cross-mingw32 debug")
+set(CMAKE_BUILD_TYPE debug)
 set(FCEUX_EXE_NAME fceuxDBG.exe)
 include(${CMAKE_SOURCE_DIR}/cmake/cross-mingw32/fceux_cross-mingw32.cmake)
diff --git a/cmake/cross-mingw32/release/CMakeLists.txt b/cmake/cross-mingw32/release/CMakeLists.txt
index 7daf882b..0e32033f 100644
--- a/cmake/cross-mingw32/release/CMakeLists.txt
+++ b/cmake/cross-mingw32/release/CMakeLists.txt
@@ -1,3 +1,4 @@
 project("fceux: cross-mingw32 release")
+set(CMAKE_BUILD_TYPE release)
 set(FCEUX_EXE_NAME fceuxREL.exe)
 include(${CMAKE_SOURCE_DIR}/cmake/cross-mingw32/fceux_cross-mingw32.cmake)
diff --git a/cmake/fceux.cmake b/cmake/fceux.cmake
index 2be10dfc..373a088b 100644
--- a/cmake/fceux.cmake
+++ b/cmake/fceux.cmake
@@ -315,6 +315,9 @@ endif(APPLE)
 if(MINGW)
   add_definitions( -DNEED_MINGW_HACKS -D_WIN32_IE=0x0600 )
 endif(MINGW)
+if(CMAKE_BUILD_TYPE STREQUAL "debug")
+  add_definitions( -D_DEBUG )
+endif(CMAKE_BUILD_TYPE STREQUAL "debug")
 if(CMAKE_COMPILER_IS_GNUCXX)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wno-write-strings -Wno-sign-compare")
 endif(CMAKE_COMPILER_IS_GNUCXX)
diff --git a/cmake/native/debug/CMakeLists.txt b/cmake/native/debug/CMakeLists.txt
index f12195b7..d21d1f2b 100644
--- a/cmake/native/debug/CMakeLists.txt
+++ b/cmake/native/debug/CMakeLists.txt
@@ -1,3 +1,4 @@
 project("fceux: native debug")
+set(CMAKE_BUILD_TYPE debug)
 set(FCEUX_EXE_NAME fceuxDBG)
 include(${CMAKE_SOURCE_DIR}/cmake/native/fceux_native.cmake)
diff --git a/cmake/native/release/CMakeLists.txt b/cmake/native/release/CMakeLists.txt
index d9a2a932..4f78c90a 100644
--- a/cmake/native/release/CMakeLists.txt
+++ b/cmake/native/release/CMakeLists.txt
@@ -1,3 +1,4 @@
 project("fceux: native release")
+set(CMAKE_BUILD_TYPE release)
 set(FCEUX_EXE_NAME fceuxREL)
 include(${CMAKE_SOURCE_DIR}/cmake/native/fceux_native.cmake)