diff --git a/lib/path-graph.js b/lib/path-graph.js
index dac581c..9b5c8dd 100644
--- a/lib/path-graph.js
+++ b/lib/path-graph.js
@@ -3,8 +3,6 @@
 
 var fill = require('lodash.fill')
 
-var MAX_GAP = 0.00011
-
 var find = function (collection, condition) {
   var element
   var i
@@ -55,10 +53,7 @@ var PathGraph = function (optimize, fillGaps) {
   this._points = []
   this._edges = []
   this._optimize = optimize
-  this._fillGaps = (fillGaps === true)
-    ? MAX_GAP
-    : fillGaps
-
+  this._fillGaps = fillGaps
   this.length = 0
 }
 
diff --git a/lib/plotter.js b/lib/plotter.js
index 024cf24..a0712cc 100644
--- a/lib/plotter.js
+++ b/lib/plotter.js
@@ -10,6 +10,8 @@ var padShape = require('./_pad-shape')
 var operate = require('./_operate')
 var boundingBox = require('./_box')
 
+var MAX_GAP = 0.00011
+
 var isFormatKey = function (key) {
   return (
     key === 'units' ||
@@ -44,8 +46,15 @@ var Plotter = function (
     backupNota: (backupNota != null)
   }
 
-  // plotting options
-  this._plotAsOutline = plotAsOutline
+  this._plotAsOutline = (plotAsOutline === true)
+    ? MAX_GAP
+    : plotAsOutline
+
+  // plotAsOutline parameter is always in mm
+  if ((units || this.format.backupUnits) === 'in') {
+    this._plotAsOutline = this._plotAsOutline / 2.54
+  }
+
   this._optimizePaths = optimizePaths || plotAsOutline
 
   this._line = 0
diff --git a/test/gerber-plotter_test.js b/test/gerber-plotter_test.js
index d1980d2..3e7bde8 100644
--- a/test/gerber-plotter_test.js
+++ b/test/gerber-plotter_test.js
@@ -92,14 +92,14 @@ describe('gerber plotter', function () {
     it('should have an outline mode option that defaults to falsey', function () {
       expect(!p._plotAsOutline).to.equal(true)
 
-      p = plotter({plotAsOutline: true})
-      expect(p._plotAsOutline).to.equal(true)
+      p = plotter({plotAsOutline: true, units: 'mm'})
+      expect(p._plotAsOutline).to.equal(0.00011)
     })
 
     it('should force optimize paths to true if plot as outline is true', function () {
-      p = plotter({plotAsOutline: true, optimizePaths: false})
-      expect(p._plotAsOutline).to.equal(true)
-      expect(p._optimizePaths).to.equal(true)
+      p = plotter({plotAsOutline: true, optimizePaths: false, units: 'mm'})
+      expect(p._plotAsOutline).to.equal(0.00011)
+      expect(p._optimizePaths).to.be.true
     })
   })
 
@@ -1870,8 +1870,7 @@ describe('gerber plotter', function () {
     })
 
     it('should be able to set a custom max gap size', function () {
-      outPlotter = plotter({plotAsOutline: 0.0011})
-
+      outPlotter = plotter({plotAsOutline: 0.0011, units: 'mm'})
       expect(outPlotter._path._fillGaps).to.equal(0.0011)
     })
   })