diff --git a/models/dns.go b/models/dns.go
index 713b6285e..1c6766b24 100644
--- a/models/dns.go
+++ b/models/dns.go
@@ -213,7 +213,7 @@ type DomainConfig struct {
 	Metadata     map[string]string `json:"meta,omitempty"`
 	Records      []*RecordConfig   `json:"records"`
 	Nameservers  []*Nameserver     `json:"nameservers,omitempty"`
-	KeepUnknown  bool              `json:"keepunknown"`
+	KeepUnknown  bool              `json:"keepunknown,omitempty"`
 }
 
 func (dc *DomainConfig) Copy() (*DomainConfig, error) {
diff --git a/pkg/js/js_test.go b/pkg/js/js_test.go
index 2bf709eca..609c0c8c2 100644
--- a/pkg/js/js_test.go
+++ b/pkg/js/js_test.go
@@ -8,7 +8,8 @@ import (
 	"testing"
 	"unicode"
 
-	"github.com/StackExchange/dnscontrol/models"
+	"github.com/tdewolff/minify"
+	minjson "github.com/tdewolff/minify/json"
 )
 
 const (
@@ -30,6 +31,8 @@ func TestParsedFiles(t *testing.T) {
 		if filepath.Ext(f.Name()) != ".js" || !unicode.IsNumber(rune(f.Name()[0])) {
 			continue
 		}
+		m := minify.New()
+		m.AddFunc("json", minjson.Minify)
 		t.Run(f.Name(), func(t *testing.T) {
 			content, err := ioutil.ReadFile(filepath.Join(testDir, f.Name()))
 			if err != nil {
@@ -43,25 +46,24 @@ func TestParsedFiles(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
+			actualJSON, err = m.Bytes("json", actualJSON)
+			if err != nil {
+				t.Fatal(err)
+			}
 			expectedFile := filepath.Join(testDir, f.Name()[:len(f.Name())-3]+".json")
 			expectedData, err := ioutil.ReadFile(expectedFile)
 			if err != nil {
 				t.Fatal(err)
 			}
-			conf = &models.DNSConfig{}
-			//unmarshal and remarshal to not require manual formatting
-			err = json.Unmarshal(expectedData, conf)
-			if err != nil {
-				t.Fatal(err)
-			}
-			expectedJSON, err := json.MarshalIndent(conf, "", "  ")
+
+			expectedJSON, err := m.String("json", string(expectedData))
 			if err != nil {
 				t.Fatal(err)
 			}
 			if string(expectedJSON) != string(actualJSON) {
 				t.Error("Expected and actual json don't match")
 				t.Log("Expected:", string(expectedJSON))
-				t.Log("Actual:", string(actualJSON))
+				t.Log("Actual  :", string(actualJSON))
 			}
 		})
 	}
diff --git a/pkg/js/parse_tests/006-transforms.json b/pkg/js/parse_tests/006-transforms.json
index 134aa2f3e..aa3cd7aaa 100644
--- a/pkg/js/parse_tests/006-transforms.json
+++ b/pkg/js/parse_tests/006-transforms.json
@@ -27,8 +27,7 @@
 		            "transform": "0.0.0.0 ~ 1.1.1.1 ~ 2.2.2.2 ~  ; 1.1.1.1 ~ 2.2.2.2 ~ 3.3.3.3,4.4.4.4,5.5.5.5 ~  ; 1.1.1.1 ~ 2.2.2.2 ~  ~ 3.3.3.3,4.4.4.4,5.5.5.5"
 		          }
 		        }
-		      ],
-		      "keepunknown": false
+		      ]
 		    }
 		  ]
 		}
\ No newline at end of file
diff --git a/pkg/js/parse_tests/007-importTransformTTL.json b/pkg/js/parse_tests/007-importTransformTTL.json
index b42526558..b0edac718 100644
--- a/pkg/js/parse_tests/007-importTransformTTL.json
+++ b/pkg/js/parse_tests/007-importTransformTTL.json
@@ -16,8 +16,7 @@
 		            "transform_table": "0.0.0.0 ~ 1.1.1.1 ~ 2.2.2.2 ~ "
 		          }
 		        }
-		      ],
-		      "keepunknown": false
+		      ]
 		    }
 		  ]
 		}
\ No newline at end of file
diff --git a/pkg/js/parse_tests/008-import.json b/pkg/js/parse_tests/008-import.json
index 63e441356..04a91c1ac 100644
--- a/pkg/js/parse_tests/008-import.json
+++ b/pkg/js/parse_tests/008-import.json
@@ -12,8 +12,7 @@
 		          "name": "@",
 		          "target": "1.2.3.4"
 		        }
-		      ],
-		      "keepunknown": false
+		      ]
 		    }
 		  ]
 		}
\ No newline at end of file
diff --git a/pkg/js/parse_tests/009-reverse.json b/pkg/js/parse_tests/009-reverse.json
index d439329a3..f4bf5a87c 100644
--- a/pkg/js/parse_tests/009-reverse.json
+++ b/pkg/js/parse_tests/009-reverse.json
@@ -6,8 +6,7 @@
 		      "name": "2.1.in-addr.arpa",
 		      "registrar": "none",
 		      "dnsProviders": {},
-		      "records": [],
-		      "keepunknown": false
+		      "records": []
 		    }
 		  ]
 		}
\ No newline at end of file
diff --git a/pkg/js/parse_tests/010-alias.json b/pkg/js/parse_tests/010-alias.json
index 6b76fa297..fc59bed03 100644
--- a/pkg/js/parse_tests/010-alias.json
+++ b/pkg/js/parse_tests/010-alias.json
@@ -12,8 +12,7 @@
 		          "name": "@",
 		          "target": "foo.com."
 		        }
-		      ],
-		      "keepunknown": false
+		      ]
 		    }
 		  ]
 		}
\ No newline at end of file
diff --git a/pkg/js/parse_tests/011-cfRedirect.json b/pkg/js/parse_tests/011-cfRedirect.json
index 729e2a0e7..bf424d463 100644
--- a/pkg/js/parse_tests/011-cfRedirect.json
+++ b/pkg/js/parse_tests/011-cfRedirect.json
@@ -17,8 +17,7 @@
 		          "name": "@",
 		          "target": "test.foo.com,https://goo.com/$1"
 		        }
-		      ],
-		      "keepunknown": false
+		      ]
 		    }
 		  ]
 		}
\ No newline at end of file
diff --git a/pkg/js/parse_tests/012-duration.json b/pkg/js/parse_tests/012-duration.json
index 100b360b3..30bd54e33 100644
--- a/pkg/js/parse_tests/012-duration.json
+++ b/pkg/js/parse_tests/012-duration.json
@@ -37,9 +37,7 @@
 		          "target": "1.2.3.4",
                   "ttl":259200
 		        }
-		      ],
-              
-		      "keepunknown": false
+		      ]
 		    }
 		  ]
 		}
\ No newline at end of file
diff --git a/pkg/js/parse_tests/013-mx.js b/pkg/js/parse_tests/013-mx.js
new file mode 100644
index 000000000..c8bb48c54
--- /dev/null
+++ b/pkg/js/parse_tests/013-mx.js
@@ -0,0 +1,3 @@
+D("foo.com","none",
+    MX("@",15,"foo.com.")
+);
\ No newline at end of file
diff --git a/pkg/js/parse_tests/013-mx.json b/pkg/js/parse_tests/013-mx.json
new file mode 100644
index 000000000..e96d45b02
--- /dev/null
+++ b/pkg/js/parse_tests/013-mx.json
@@ -0,0 +1,19 @@
+{
+    "registrars": [],
+    "dns_providers": [],
+    "domains": [
+        {
+            "name": "foo.com",
+            "registrar": "none",
+            "dnsProviders": {},
+            "records": [
+                {
+                    "type": "MX",
+                    "name": "@",
+                    "target": "foo.com.",
+                    "mxpreference": 15
+                }
+            ]
+        }
+    ]
+}
\ No newline at end of file