diff --git a/configure b/configure
index bfdca8b814..52408ed307 100755
--- a/configure
+++ b/configure
@@ -7392,22 +7392,31 @@ if test "$ccache_cpp2" = "yes"; then
   echo "export CCACHE_CPP2=y" >> $config_host_mak
 fi
 
-# build tree in object directory in case the source is not in the current directory
+# If we're using a separate build tree, set it up now.
+# DIRS are directories which we simply mkdir in the build tree;
+# LINKS are things to symlink back into the source tree
+# (these can be both files and directories).
+# Caution: do not add files or directories here using wildcards. This
+# will result in problems later if a new file matching the wildcard is
+# added to the source tree -- nothing will cause configure to be rerun
+# so the build tree will be missing the link back to the new file, and
+# tests might fail. Prefer to keep the relevant files in their own
+# directory and symlink the directory instead.
 DIRS="tests tests/tcg tests/tcg/cris tests/tcg/lm32 tests/libqos tests/qapi-schema tests/tcg/xtensa tests/qemu-iotests tests/vm"
 DIRS="$DIRS tests/fp"
 DIRS="$DIRS docs docs/interop fsdev scsi"
 DIRS="$DIRS pc-bios/optionrom pc-bios/spapr-rtas pc-bios/s390-ccw"
 DIRS="$DIRS roms/seabios roms/vgabios"
-FILES="Makefile tests/tcg/Makefile qdict-test-data.txt"
-FILES="$FILES tests/tcg/cris/Makefile tests/tcg/cris/.gdbinit"
-FILES="$FILES tests/tcg/lm32/Makefile tests/tcg/xtensa/Makefile po/Makefile"
-FILES="$FILES tests/fp/Makefile"
-FILES="$FILES pc-bios/optionrom/Makefile pc-bios/keymaps"
-FILES="$FILES pc-bios/spapr-rtas/Makefile"
-FILES="$FILES pc-bios/s390-ccw/Makefile"
-FILES="$FILES roms/seabios/Makefile roms/vgabios/Makefile"
-FILES="$FILES pc-bios/qemu-icon.bmp"
-FILES="$FILES .gdbinit scripts" # scripts needed by relative path in .gdbinit
+LINKS="Makefile tests/tcg/Makefile qdict-test-data.txt"
+LINKS="$LINKS tests/tcg/cris/Makefile tests/tcg/cris/.gdbinit"
+LINKS="$LINKS tests/tcg/lm32/Makefile tests/tcg/xtensa/Makefile po/Makefile"
+LINKS="$LINKS tests/fp/Makefile"
+LINKS="$LINKS pc-bios/optionrom/Makefile pc-bios/keymaps"
+LINKS="$LINKS pc-bios/spapr-rtas/Makefile"
+LINKS="$LINKS pc-bios/s390-ccw/Makefile"
+LINKS="$LINKS roms/seabios/Makefile roms/vgabios/Makefile"
+LINKS="$LINKS pc-bios/qemu-icon.bmp"
+LINKS="$LINKS .gdbinit scripts" # scripts needed by relative path in .gdbinit
 for bios_file in \
     $source_path/pc-bios/*.bin \
     $source_path/pc-bios/*.lid \
@@ -7419,10 +7428,10 @@ for bios_file in \
     $source_path/pc-bios/u-boot.* \
     $source_path/pc-bios/palcode-*
 do
-    FILES="$FILES pc-bios/$(basename $bios_file)"
+    LINKS="$LINKS pc-bios/$(basename $bios_file)"
 done
 mkdir -p $DIRS
-for f in $FILES ; do
+for f in $LINKS ; do
     if [ -e "$source_path/$f" ] && [ "$pwd_is_source_path" != "y" ]; then
         symlink "$source_path/$f" "$f"
     fi