diff --git a/cmake/modules/LibffiUtils.cmake b/cmake/modules/LibffiUtils.cmake
index d4266fc..b3fa697 100644
--- a/cmake/modules/LibffiUtils.cmake
+++ b/cmake/modules/LibffiUtils.cmake
@@ -56,7 +56,7 @@
     list(APPEND asm_srcs "${libffi_srcroot}/src/x86/unix64.S")
     list(APPEND asm_srcs "${libffi_srcroot}/src/x86/win64.S")
   endif()
-  set_source_files_properties(${asm_srcs} PROPERTIES LANGUAGE C)
+  set_source_files_properties(${asm_srcs} PROPERTIES LANGUAGE ASM)
 
   # Set target based on arch.
   if(HAVE_64BIT AND ${llarch} STREQUAL "aarch64")