diff --git a/spec/config-spec.coffee b/spec/config-spec.coffee
index 277a8a2d3..f3a3d6e79 100644
--- a/spec/config-spec.coffee
+++ b/spec/config-spec.coffee
@@ -32,7 +32,7 @@ describe "Config", ->
       config.set("foo.bar.baz", 42)
 
       expect(config.save).toHaveBeenCalled()
-      expect(observeHandler).toHaveBeenCalledWith 42
+      expect(observeHandler).toHaveBeenCalledWith 42, {previous: undefined}
 
     describe "when the value equals the default value", ->
       it "does not store the value", ->
@@ -54,7 +54,7 @@ describe "Config", ->
 
       expect(config.pushAtKeyPath("foo.bar.baz", "b")).toBe 2
       expect(config.get("foo.bar.baz")).toEqual ["a", "b"]
-      expect(observeHandler).toHaveBeenCalledWith config.get("foo.bar.baz")
+      expect(observeHandler).toHaveBeenCalledWith config.get("foo.bar.baz"), {previous: ['a']}
 
   describe ".removeAtKeyPath(keyPath, value)", ->
     it "removes the given value from the array at the key path and updates observers", ->
@@ -65,7 +65,7 @@ describe "Config", ->
 
       expect(config.removeAtKeyPath("foo.bar.baz", "b")).toEqual ["a", "c"]
       expect(config.get("foo.bar.baz")).toEqual ["a", "c"]
-      expect(observeHandler).toHaveBeenCalledWith config.get("foo.bar.baz")
+      expect(observeHandler).toHaveBeenCalledWith config.get("foo.bar.baz"), {previous: ['a', 'b', 'c']}
 
   describe ".getPositiveInt(keyPath, defaultValue)", ->
     it "returns the proper current or default value", ->
@@ -142,26 +142,26 @@ describe "Config", ->
     it "fires the callback every time the observed value changes", ->
       observeHandler.reset() # clear the initial call
       config.set('foo.bar.baz', "value 2")
-      expect(observeHandler).toHaveBeenCalledWith("value 2")
+      expect(observeHandler).toHaveBeenCalledWith("value 2", {previous: 'value 1'})
       observeHandler.reset()
 
       config.set('foo.bar.baz', "value 1")
-      expect(observeHandler).toHaveBeenCalledWith("value 1")
+      expect(observeHandler).toHaveBeenCalledWith("value 1", {previous: 'value 2'})
 
     it "fires the callback when the observed value is deleted", ->
       observeHandler.reset() # clear the initial call
       config.set('foo.bar.baz', undefined)
-      expect(observeHandler).toHaveBeenCalledWith(undefined)
+      expect(observeHandler).toHaveBeenCalledWith(undefined, {previous: 'value 1'})
 
     it "fires the callback when the full key path goes into and out of existence", ->
       observeHandler.reset() # clear the initial call
       config.set("foo.bar", undefined)
 
-      expect(observeHandler).toHaveBeenCalledWith(undefined)
+      expect(observeHandler).toHaveBeenCalledWith(undefined, {previous: 'value 1'})
       observeHandler.reset()
 
       config.set("foo.bar.baz", "i'm back")
-      expect(observeHandler).toHaveBeenCalledWith("i'm back")
+      expect(observeHandler).toHaveBeenCalledWith("i'm back", {previous: undefined})
 
   describe ".initializeConfigDirectory()", ->
     beforeEach ->