diff --git a/lib/morris.grid.coffee b/lib/morris.grid.coffee
index b7b46e4..8cc471b 100644
--- a/lib/morris.grid.coffee
+++ b/lib/morris.grid.coffee
@@ -151,30 +151,9 @@ class Morris.Grid extends Morris.EventEmitter
       @xmin -= 1
       @xmax += 1
 
-    # Compute the vertical range of the graph if desired
-    if typeof @options.ymax is 'string'
-      if @options.ymax[0..3] is 'auto'
-        # use Array.concat to flatten arrays and find the max y value
-        if @options.ymax.length > 5
-          @ymax = parseInt(@options.ymax[5..], 10)
-          @ymax = Math.max(ymax, @ymax) if ymax?
-        else
-          @ymax = if ymax? then ymax else 0
-      else
-        @ymax = parseInt(@options.ymax, 10)
-    else
-      @ymax = @options.ymax
-    if typeof @options.ymin is 'string'
-      if @options.ymin[0..3] is 'auto'
-        if @options.ymin.length > 5
-          @ymin = parseInt(@options.ymin[5..], 10)
-          @ymin = Math.min(ymin, @ymin) if ymin?
-        else
-          @ymin = if ymin isnt null then ymin else 0
-      else
-        @ymin = parseInt(@options.ymin, 10)
-    else
-      @ymin = @options.ymin
+    @ymin = @yboundary('min', ymin)
+    @ymax = @yboundary('max', ymax)
+
     if @ymin is @ymax
       @ymin -= 1 if ymin
       @ymax += 1
@@ -188,6 +167,21 @@ class Morris.Grid extends Morris.EventEmitter
     @dirty = true
     @redraw() if redraw
 
+  yboundary: (boundaryType, currentValue) ->
+    boundaryOption = @options["y#{boundaryType}"]
+    if typeof boundaryOption is 'string'
+      if boundaryOption[0..3] is 'auto'
+        if boundaryOption.length > 5
+          suggestedValue = parseInt(boundaryOption[5..], 10)
+          return suggestedValue unless currentValue?
+          Math[boundaryType](currentValue, suggestedValue)
+        else
+          if currentValue? then currentValue else 0
+      else
+        parseInt(boundaryOption, 10)
+    else
+      boundaryOption
+
   _calc: ->
     w = @el.width()
     h = @el.height()
diff --git a/spec/lib/grid/set_data_spec.coffee b/spec/lib/grid/set_data_spec.coffee
index c7e0a1e..57150a7 100644
--- a/spec/lib/grid/set_data_spec.coffee
+++ b/spec/lib/grid/set_data_spec.coffee
@@ -12,14 +12,16 @@ describe 'Morris.Grid#setData', ->
     my_data.should.deep.equal expected_data
 
   describe 'ymin/ymax', ->
-
-    it 'should use a user-specified minimum and maximum value', ->
-      line = Morris.Line
+    beforeEach ->
+      @defaults = 
         element: 'graph'
-        data: [{x: 1, y: 1}]
         xkey: 'x'
         ykeys: ['y', 'z']
         labels: ['y', 'z']
+
+    it 'should use a user-specified minimum and maximum value', ->
+      line = Morris.Line $.extend @defaults,
+        data: [{x: 1, y: 1}]
         ymin: 10
         ymax: 20
       line.ymin.should.equal 10
@@ -28,22 +30,16 @@ describe 'Morris.Grid#setData', ->
     describe 'auto', ->
 
       it 'should automatically calculate the minimum and maximum value', ->
-        line = Morris.Line
-          element: 'graph'
+        line = Morris.Line $.extend @defaults,
           data: [{x: 1, y: 10}, {x: 2, y: 15}, {x: 3, y: null}, {x: 4}]
-          xkey: 'x'
-          ykeys: ['y', 'z']
-          labels: ['y', 'z']
           ymin: 'auto'
           ymax: 'auto'
         line.ymin.should.equal 10
         line.ymax.should.equal 15
-        line = Morris.Line
-          element: 'graph'
+
+      it 'should automatically calculate the minimum and maximum value given no y data', ->
+        line = Morris.Line $.extend @defaults,
           data: [{x: 1}, {x: 2}, {x: 3}, {x: 4}]
-          xkey: 'x'
-          ykeys: ['y', 'z']
-          labels: ['y', 'z']
           ymin: 'auto'
           ymax: 'auto'
         line.ymin.should.equal 0
@@ -52,44 +48,32 @@ describe 'Morris.Grid#setData', ->
     describe 'auto [n]', ->
 
       it 'should automatically calculate the minimum and maximum value', ->
-        line = Morris.Line
-          element: 'graph'
+        line = Morris.Line $.extend @defaults,
           data: [{x: 1, y: 10}, {x: 2, y: 15}, {x: 3, y: null}, {x: 4}]
-          xkey: 'x'
-          ykeys: ['y', 'z']
-          labels: ['y', 'z']
           ymin: 'auto 11'
           ymax: 'auto 13'
         line.ymin.should.equal 10
         line.ymax.should.equal 15
-        line = Morris.Line
-          element: 'graph'
+
+      it 'should automatically calculate the minimum and maximum value given no data', ->
+        line = Morris.Line $.extend @defaults,
           data: [{x: 1}, {x: 2}, {x: 3}, {x: 4}]
-          xkey: 'x'
-          ykeys: ['y', 'z']
-          labels: ['y', 'z']
           ymin: 'auto 11'
           ymax: 'auto 13'
         line.ymin.should.equal 11
         line.ymax.should.equal 13
 
       it 'should use a user-specified minimum and maximum value', ->
-        line = Morris.Line
-          element: 'graph'
+        line = Morris.Line $.extend @defaults,
           data: [{x: 1, y: 10}, {x: 2, y: 15}, {x: 3, y: null}, {x: 4}]
-          xkey: 'x'
-          ykeys: ['y', 'z']
-          labels: ['y', 'z']
           ymin: 'auto 5'
           ymax: 'auto 20'
         line.ymin.should.equal 5
         line.ymax.should.equal 20
-        line = Morris.Line
-          element: 'graph'
+
+      it 'should use a user-specified minimum and maximum value given no data', ->
+        line = Morris.Line $.extend @defaults,
           data: [{x: 1}, {x: 2}, {x: 3}, {x: 4}]
-          xkey: 'x'
-          ykeys: ['y', 'z']
-          labels: ['y', 'z']
           ymin: 'auto 5'
           ymax: 'auto 20'
         line.ymin.should.equal 5