diff --git a/sdl.m4 b/sdl.m4
index ada3a4165..09b72e448 100644
--- a/sdl.m4
+++ b/sdl.m4
@@ -52,8 +52,10 @@ AC_ARG_ENABLE(sdltest, [  --disable-sdltest       Do not try to compile and run
            sed 's/\([[0-9]]*\).\([[0-9]]*\).\([[0-9]]*\)/\3/'`
     if test "x$enable_sdltest" = "xyes" ; then
       ac_save_CFLAGS="$CFLAGS"
+      ac_save_CXXFLAGS="$CXXFLAGS"
       ac_save_LIBS="$LIBS"
       CFLAGS="$CFLAGS $SDL_CFLAGS"
+      CXXFLAGS="$CXXFLAGS $SDL_CFLAGS"
       LIBS="$LIBS $SDL_LIBS"
 dnl
 dnl Now check if the installed SDL is sufficiently new. (Also sanity
@@ -138,6 +140,7 @@ int main (int argc, char *argv[])
        else
           echo "*** Could not run SDL test program, checking why..."
           CFLAGS="$CFLAGS $SDL_CFLAGS"
+          CXXFLAGS="$CXXFLAGS $SDL_CFLAGS"
           LIBS="$LIBS $SDL_LIBS"
           AC_TRY_LINK([
 #include <stdio.h>
@@ -162,10 +165,12 @@ int main(int argc, char *argv[])
           echo "*** or that you have moved SDL since it was installed. In the latter case, you"
           echo "*** may want to edit the sdl-config script: $SDL_CONFIG" ])
           CFLAGS="$ac_save_CFLAGS"
+          CXXFLAGS="$ac_save_CXXFLAGS"
           LIBS="$ac_save_LIBS"
        fi
      fi
      SDL_CFLAGS=""
+     SDL_CXXFLAGS=""
      SDL_LIBS=""
      ifelse([$3], , :, [$3])
   fi