diff --git a/spec/package-manager-spec.coffee b/spec/package-manager-spec.coffee
index e6848ef03..46d1d11ee 100644
--- a/spec/package-manager-spec.coffee
+++ b/spec/package-manager-spec.coffee
@@ -1026,6 +1026,16 @@ describe "PackageManager", ->
         expect(atom.packages.enablePackage("this-doesnt-exist")).toBeNull()
         expect(console.warn.callCount).toBe 1
 
+      it "does not disable an already disabled package", ->
+        packageName = 'package-with-main'
+        atom.config.pushAtKeyPath('core.disabledPackages', packageName)
+        atom.packages.observeDisabledPackages()
+        expect(atom.config.get('core.disabledPackages')).toContain packageName
+
+        atom.packages.disablePackage(packageName)
+        packagesDisabled = atom.config.get('core.disabledPackages').filter((pack) -> pack is packageName)
+        expect(packagesDisabled.length).toEqual 1
+
     describe "with themes", ->
       didChangeActiveThemesHandler = null
 
diff --git a/src/package-manager.coffee b/src/package-manager.coffee
index 6772178af..1ecdc5448 100644
--- a/src/package-manager.coffee
+++ b/src/package-manager.coffee
@@ -199,7 +199,10 @@ class PackageManager
   # Returns the {Package} that was disabled or null if it isn't loaded.
   disablePackage: (name) ->
     pack = @loadPackage(name)
-    pack?.disable()
+
+    unless @isPackageDisabled(name)
+      pack?.disable()
+
     pack
 
   # Public: Is the package with the given name disabled?