diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4df07b4..81a48c8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -39,6 +39,9 @@ set(CMAKE_EXE_LINKER_FLAGS "-ffreestanding -nostdlib")
 
 # perform data type checks
 include(CheckTypeSize)
+if(64BIT)
+	check_type_size("uint64_t" UINT64_T)
+endif()
 check_type_size("uint32_t" UINT32_T)
 check_type_size("uint16_t" UINT16_T)
 check_type_size("uint8_t" UINT8_T)
diff --git a/toolchains/i686-elf.cmake b/toolchains/i686-elf.cmake
index 8e260bc..6c7a296 100644
--- a/toolchains/i686-elf.cmake
+++ b/toolchains/i686-elf.cmake
@@ -6,3 +6,5 @@ set(CMAKE_C_FLAGS "-ffreestanding -fno-builtin" CACHE STRING "C flags for test c
 set(CMAKE_EXE_LINKER_FLAGS "-ffreestanding -nostdlib" CACHE STRING "Linker flags for test compilation.")
 set(CMAKE_TRY_COMPILE_PLATFORM_VARIABLES CMAKE_C_FLAGS)
 set(CMAKE_ASM_COMPILER i686-elf-as)
+
+set(64BIT FALSE CACHE BOOL "Whether the architecture supports 64-bit.")