diff --git a/tools/sort_symfile.sh b/tools/sort_symfile.sh
index d53150faa..82fced560 100755
--- a/tools/sort_symfile.sh
+++ b/tools/sort_symfile.sh
@@ -1,10 +1,12 @@
 #!/bin/sh
-sed $1 \
+sed \
     -e "s/^..:[0-3]/0_ROM0@&/g" \
     -e "s/^..:[4-7]/1_ROMX@&/g" \
     -e "s/^..:[8-9]/2_VRAM@&/g" \
     -e "s/^..:[A-B]/3_SRAM@&/g" \
     -e "s/^00:[C-D]/4_WRAM0@&/g" \
     -e "s/^..:[D-D]/5_WRAMX@&/g" \
+    $1 \
 | sort -o $1
-sed -i $1 -e "s/^\w*@//g"
+TEMP_FILE=$(mktemp)
+sed -e "s/^.*@//g" $1 > $TEMP_FILE && mv $TEMP_FILE $1