diff --git a/prism/etc/scripts/prism3to4 b/prism/etc/scripts/prism3to4
index 1d56b8e5..d81661bb 100755
--- a/prism/etc/scripts/prism3to4
+++ b/prism/etc/scripts/prism3to4
@@ -1,17 +1,23 @@
 #!/bin/sh
 
+# Script for conversion of old PRISM files (Linux/Solaris)
+
 if [ "$1" = "" ]; then
   echo "Usage: prism3to4 <file> [<outfile>]"
   exit
 fi
 
+# Run using main PRISM script with this class
+PRISM_MAINCLASS="parser.Prism3To4"
+export PRISM_MAINCLASS
+
 if [ "$2" = "" ]; then
-  java -cp ~/prism-parser/classes parser.Prism3To4 "$1"
+  prism "$1"
 else
   if [ "$2" = "$1" ]; then
-    ( java -cp ~/prism-parser/classes parser.Prism3To4 "$1" > "$2".new && mv "$2".new "$2" ) || rm "$2".new
+    ( prism "$1" > "$2".new && mv "$2".new "$2" ) || rm "$2".new
   else
-    java -cp ~/prism-parser/classes parser.Prism3To4 "$1" > "$2"
+    prism "$1" > "$2"
   fi
 fi