Fix typo
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b87094e..80a013c 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2432,7 +2432,7 @@
   # Even though MSVC has __restrict, it can't be used in all the same contexts as the C99 restrict keyword
   TARGET_COMPILE_DEFINITIONS(XNNPACK PRIVATE "restrict=")
   IF(${CMAKE_VERSION} VERSION_LESS "3.8.0")
-    IF(CMAKE_BUILD_TYPE STREQUAL "Debug")
+    IF(NOT CMAKE_BUILD_TYPE STREQUAL "Debug")
       SET_PROPERTY(SOURCE ${XNNPACK_MICROKERNEL_SRCS} APPEND_STRING PROPERTY COMPILE_FLAGS " /O2 ")
       SET_PROPERTY(SOURCE ${XNNPACK_HOT_SRCS} APPEND_STRING PROPERTY COMPILE_FLAGS " /O2 ")
       SET_PROPERTY(SOURCE ${XNNPACK_COLD_SRCS} APPEND_STRING PROPERTY COMPILE_FLAGS " /O1 ")