diff --git a/cmake/c_check.cmake b/cmake/c_check.cmake
index 5669c723a..07ed8a178 100644
--- a/cmake/c_check.cmake
+++ b/cmake/c_check.cmake
@@ -20,10 +20,16 @@
 # TODO: detect NEED_FU
 set(NEED_FU 1)
 
-string(TOUPPER ${CMAKE_SYSTEM_NAME} CMAKE_SYSTEM_NAME_UC)
+# Convert CMake vars into the format that OpenBLAS expects
+string(TOUPPER ${CMAKE_SYSTEM_NAME} HOST_OS)
+set(HOST_ARCH ${CMAKE_SYSTEM_PROCESSOR})
+if (${HOST_ARCH} STREQUAL "AMD64")
+  set(HOST_ARCH "X86_64")
+endif ()
+
 file(WRITE ${TARGET_CONF}
-  "#define OS_${CMAKE_SYSTEM_NAME_UC}\t1\n"
-  "#define ARCH_${CMAKE_SYSTEM_PROCESSOR}\t1\n"
+  "#define OS_${HOST_OS}\t1\n"
+  "#define ARCH_${HOST_ARCH}\t1\n"
   "#define C_${CMAKE_CXX_COMPILER_ID}\t1\n"
   "#define __${BINARY}BIT__\t1\n"
   "#define FUNDERSCORE\t${NEED_FU}\n")