diff --git a/Filters/VLBIABType.reader b/Filters/VLBIABType.reader
index 38defb2..dcfe715 100755
--- a/Filters/VLBIABType.reader
+++ b/Filters/VLBIABType.reader
@@ -61,17 +61,17 @@ KEY = [[ 0, 1],
        [ 3,-1], [-2,-1], [ 5,-1], [ 0,-1], [-5,-1], [ 2,-1],
        [ 4,-1], [ 6,-1], [ 3,-1], [ 5,-1], [ 7,-1]]
 
-$stdin.read(1) # Skip 1 Byte
-titleLen = $stdin.read(1)[0]
-OUTPUT['title'] = $stdin.read(titleLen)
+INFILE.read(1) # Skip 1 Byte
+titleLen = INFILE.read(1)[0]
+OUTPUT['title'] = INFILE.read(titleLen)
 
-$stdin.read(2) # Skip 2 Bytes
-gr               = $stdin.read(1)[0]-1
+INFILE.read(2) # Skip 2 Bytes
+gr               = INFILE.read(1)[0]-1
 groove           = GROOVE[gr] || ['Swing']
-key = KEY[$stdin.read(1)[0]]
+key = KEY[INFILE.read(1)[0]]
 PROP['key']      = key[0]
 PROP['mode']     = key[1]
-OUTPUT['tempo']  = $stdin.read(1)[0] 
+OUTPUT['tempo']  = INFILE.read(1)[0] 
 
 #
 # Style map - not processed yet
@@ -79,12 +79,12 @@ OUTPUT['tempo']  = $stdin.read(1)[0]
 STYLES = []
 i=0
 while i < 256
-  st = $stdin.read(1)[0]
+  st = INFILE.read(1)[0]
   if st > 0
     STYLES[i-1] = st
     i          += 1
   else
-    i          += $stdin.read(1)[0]
+    i          += INFILE.read(1)[0]
   end
 end
 
@@ -282,12 +282,12 @@ EXT   = [
 STEPS = []
 i     = 0
 while i < 1020
-  ex = $stdin.read(1)[0]
+  ex = INFILE.read(1)[0]
   if ex > 0
     STEPS[i] = EXT[ex]
     i       += 1
   else
-    i       += $stdin.read(1)[0]
+    i       += INFILE.read(1)[0]
   end
 end
 
@@ -297,7 +297,7 @@ CHORDS  = []
 ROOTS   = []
 i       = 0
 while i < 1021
-  cr = $stdin.read(1)[0]
+  cr = INFILE.read(1)[0]
   if cr > 0
     CHORDS[i] = PITCHES[cr % 18]
     if cr > 18
@@ -305,15 +305,15 @@ while i < 1021
     end
     i       += 1
   else
-    i       += $stdin.read(1)[0]
+    i       += INFILE.read(1)[0]
   end
 end
 
-$stdin.read(1) # Start measure
-numMeasures = $stdin.read(1)[0]
-numRepeats  = $stdin.read(1)[0]
+INFILE.read(1) # Start measure
+numMeasures = INFILE.read(1)[0]
+numRepeats  = INFILE.read(1)[0]
 
-biab      = $stdin.read
+biab      = INFILE.read
 
 styleFile = nil
 if biab =~ /B.(.{1,8})\.STY/m
diff --git a/Filters/VLLilypondType.reader b/Filters/VLLilypondType.reader
index c6780b7..f03bcb3 100755
--- a/Filters/VLLilypondType.reader
+++ b/Filters/VLLilypondType.reader
@@ -14,7 +14,7 @@ OUTPUT = {'measures' => []}
 # Lex
 #
 tokens = []
-$stdin.each do |line|
+INFILE.each do |line|
   line.chomp!.sub!(/%.*/, "")
   line.scan(%r$\G\s*(\{|\}|\(|\)|\||=|~|<<|>>|--|#'|#\(|##t|##f|\\\w+|\".*?\"|\w[-+\w\d.',:*/]+|.)$) do |token|
     tokens.push(token[0])
diff --git a/Filters/VLMusicXMLType.reader b/Filters/VLMusicXMLType.reader
index 2a56620..77fc881 100755
--- a/Filters/VLMusicXMLType.reader
+++ b/Filters/VLMusicXMLType.reader
@@ -444,7 +444,7 @@ class MusicXMLListener
 end
 
 listener = MusicXMLListener.new
-REXML::Document.parse_stream($stdin, listener)
+REXML::Document.parse_stream(INFILE, listener)
 writePlist($stdout, OUTPUT)
 
 # Local Variables:
diff --git a/Filters/VLMusicXMLType.writer b/Filters/VLMusicXMLType.writer
index 3f489dd..0d129f7 100755
--- a/Filters/VLMusicXMLType.writer
+++ b/Filters/VLMusicXMLType.writer
@@ -7,7 +7,7 @@ require File.dirname($0)+'/plistReader'
 require File.dirname($0)+'/vl'
 require 'rexml/document'
 
-INPUT = readPlist($stdin)
+INPUT = readPlist(INFILE)
 
 $USE_FLATS = false
 $DIVISIONS = 3
diff --git a/Filters/vl.rb b/Filters/vl.rb
index 933d045..30abb39 100644
--- a/Filters/vl.rb
+++ b/Filters/vl.rb
@@ -112,7 +112,7 @@ class VL
       @denom /= g
     end
 
-    def -()
+    def -@()
       return Fract.new(-@num, @denom)
     end
 
@@ -129,3 +129,9 @@ class VL
     end
   end
 end
+
+if ARGV.size > 0
+  INFILE = File.new(ARGV[0], "r")
+else
+  INFILE = $stdin
+end