@@ -2606,14 +2606,23 @@ EOF

     check_asm bswap '"bswap %%eax" ::: "%eax"'

-    YASMFLAGS="-f $objformat"

-    enabled     x86_64        && append YASMFLAGS "-m amd64"

-    enabled     pic           && append YASMFLAGS "-DPIC"

-    test -n "$extern_prefix"  && append YASMFLAGS "-DPREFIX"

-    case "$objformat" in

-        elf) enabled debug && append YASMFLAGS "-g dwarf2" ;;

-    esac

     if ! disabled_any asm mmx yasm; then

+        if check_cmd $yasmexe --version; then

+            enabled x86_64 && yasm_extra="-m amd64"

+            yasm_debug="-g dwarf2"

+        elif check_cmd nasm -v; then

+            yasmexe=nasm

+            yasm_debug="-g -F dwarf"

+            enabled x86_64 && test "$objformat" = elf && objformat=elf64

+        fi

+

+        YASMFLAGS="-f $objformat $yasm_extra"

+        enabled pic               && append YASMFLAGS "-DPIC"

+        test -n "$extern_prefix"  && append YASMFLAGS "-DPREFIX"

+        case "$objformat" in

+            elf*) enabled debug && append YASMFLAGS $yasm_debug ;;

+        esac

+

         check_yasm "pabsw xmm0, xmm0" && enable yasm ||

             die "yasm not found, use --disable-yasm for a crippled build"

     fi