diff --git a/nc_optimisation.cmake b/nc_optimisation.cmake
index 27125c1..66e9ba0 100644
--- a/nc_optimisation.cmake
+++ b/nc_optimisation.cmake
@@ -97,7 +97,7 @@ elseif (${host_cpu} STREQUAL "i686")
     append_compile_flag(-mcmov)
     append_compile_flag(-mfpmath=sse)
 else ()
-    message (FATAL_ERROR "unknown HOST_CPU '${host_cpu}'")
+    message (WARNING "Unknown architecture. Not attempting performance options")
 endif ()