diff --git a/makefile b/makefile
index 8384c6d..dfd95f7 100644
--- a/makefile
+++ b/makefile
@@ -15,6 +15,7 @@ FEATURE = $(subst .ttf,.fea,$(subst $(OBJDIR)/,$(OBJDIR)/.pass0-,$(TARGETS)))
 PASS1   = $(subst $(OBJDIR)/,$(OBJDIR)/.pass1-,$(TARGETS))
 PASS2   = $(subst $(OBJDIR)/,$(OBJDIR)/.pass2-,$(TARGETS))
 PASS3   = $(subst $(OBJDIR)/,$(OBJDIR)/.pass3-,$(TARGETS))
+PASS4   = $(subst $(OBJDIR)/,$(OBJDIR)/.pass4-,$(TARGETS))
 
 FILES = $(SUPPORT_FILES) buildglyphs.js
 
@@ -51,8 +52,10 @@ $(PASS2) : $(OBJDIR)/.pass2-%.ttf : pass2-smartround.js $(OBJDIR)/.pass1-%.ttf
 	node $^ $@ --upm $(TARGETUPM)
 $(PASS3) : $(OBJDIR)/.pass3-%.ttf : pass3-finalize.py $(OBJDIR)/.pass2-%.ttf
 	fontforge -quiet -script $^ $@ $(TARGETUPM)
-$(TARGETS) : $(OBJDIR)/%.ttf : $(OBJDIR)/.pass3-%.ttf
+$(PASS4) : $(OBJDIR)/.pass4-%.ttf : $(OBJDIR)/.pass3-%.ttf
 	ttfautohint $< $@
+$(TARGETS) : $(OBJDIR)/%.ttf : pass4-fixmeta.js $(OBJDIR)/.pass4-%.ttf
+	node $^ $@
 
 update : $(FILES)
 
diff --git a/pass4-fixmeta.js b/pass4-fixmeta.js
new file mode 100644
index 0000000..6abde61
--- /dev/null
+++ b/pass4-fixmeta.js
@@ -0,0 +1,39 @@
+var fs = require('fs');
+var TTFReader = require('node-sfnt').TTFReader;
+var TTFWriter = require('node-sfnt').TTFWriter;
+function toArrayBuffer(buffer) {
+    var length = buffer.length;
+    var view = new DataView(new ArrayBuffer(length), 0, length);
+    for (var i = 0, l = length; i < l; i++) {
+        view.setUint8(i, buffer[i], false);
+    }
+    return view.buffer;
+}
+function toBuffer(arrayBuffer) {
+    var length = arrayBuffer.byteLength;
+    var view = new DataView(arrayBuffer, 0, length);
+    var buffer = new Buffer(length);
+    for (var i = 0, l = length; i < l; i++) {
+        buffer[i] = view.getUint8(i, false);
+    }
+    return buffer;
+}
+
+var options = {preserveOS2Version: true, preserveXAvgCharWidth: true, writeUnknownTables: true, hinting: true}
+
+function readttf(file) {
+    var data = fs.readFileSync(file);
+    var buffer = toArrayBuffer(data);
+    var ttf = (new TTFReader(options)).read(buffer);
+    return ttf;
+}
+
+function writettf(ttf, file){
+    var buffer = new TTFWriter(options).write(ttf);
+    fs.writeFileSync(file, toBuffer(buffer));
+}
+
+var ttf = readttf(process.argv[2]);
+// Fixes xAvgCharWidth
+if(process.argv[3]) ttf['OS/2'].xAvgCharWidth = ttf.head.unitsPerEm / 2; // 0.5em
+fs.writeFileSync(process.argv[3], toBuffer(new TTFWriter(options).write(ttf)));
\ No newline at end of file