diff --git a/plugins/kernel_v2/config/disk.rb b/plugins/kernel_v2/config/disk.rb
index 0f84633c5..afdcfdc7c 100644
--- a/plugins/kernel_v2/config/disk.rb
+++ b/plugins/kernel_v2/config/disk.rb
@@ -102,9 +102,9 @@ module VagrantPlugins
         @file = nil if @file == UNSET_VALUE
 
         if @primary == UNSET_VALUE
-          @primary = true
-        else
           @primary = false
+        else
+          @primary = true
         end
 
         # Give the disk a default name if unset
diff --git a/test/unit/plugins/kernel_v2/config/disk_test.rb b/test/unit/plugins/kernel_v2/config/disk_test.rb
index dccfd14b6..88640d274 100644
--- a/test/unit/plugins/kernel_v2/config/disk_test.rb
+++ b/test/unit/plugins/kernel_v2/config/disk_test.rb
@@ -43,9 +43,9 @@ describe VagrantPlugins::Kernel_V2::VagrantConfigDisk do
       expect(subject.type).to eq(type)
     end
 
-    it "defaults to primray disk" do
+    it "defaults to non-primray disk" do
       subject.finalize!
-      expect(subject.primary).to eq(true)
+      expect(subject.primary).to eq(false)
     end
   end