diff --git a/src/TypeFormatter/LiteralUnionTypeFormatter.ts b/src/TypeFormatter/LiteralUnionTypeFormatter.ts
index e7cf4d844..51935c98a 100644
--- a/src/TypeFormatter/LiteralUnionTypeFormatter.ts
+++ b/src/TypeFormatter/LiteralUnionTypeFormatter.ts
@@ -18,6 +18,7 @@ export class LiteralUnionTypeFormatter implements SubTypeFormatter {
         let hasString = false;
         let preserveLiterals = false;
         let allStrings = true;
+        let hasNull = false;
 
         const flattenedTypes = flattenTypes(type);
 
@@ -27,9 +28,10 @@ export class LiteralUnionTypeFormatter implements SubTypeFormatter {
                 hasString = true;
                 preserveLiterals = preserveLiterals || t.getPreserveLiterals();
                 return false;
-            }
-
-            if (t instanceof LiteralType && !t.isString()) {
+            } else if (t instanceof NullType) {
+                hasNull = true;
+                return true;
+            } else if (t instanceof LiteralType && !t.isString()) {
                 allStrings = false;
             }
 
@@ -38,7 +40,7 @@ export class LiteralUnionTypeFormatter implements SubTypeFormatter {
 
         if (allStrings && hasString && !preserveLiterals) {
             return {
-                type: "string",
+                type: hasNull ? ["string", "null"] : "string",
             };
         }
 
diff --git a/test/valid-data/string-literals-hack/main.ts b/test/valid-data/string-literals-hack/main.ts
index 0e6fc4eab..57489b475 100644
--- a/test/valid-data/string-literals-hack/main.ts
+++ b/test/valid-data/string-literals-hack/main.ts
@@ -5,6 +5,7 @@ export type MyObject = {
     stringWithNull: string | null;
     literalWithNull: "foo" | "bar" | null;
     literalWithString: "foo" | "bar" | string;
+    literalWithStringAndNull: "foo" | "bar" | string | null;
     withRef: "foo" | Union;
     withRefWithString: Union | string;
     withHack: "foo" | "bar" | (string & {});
diff --git a/test/valid-data/string-literals-hack/schema.json b/test/valid-data/string-literals-hack/schema.json
index 722779f4d..388eceac0 100644
--- a/test/valid-data/string-literals-hack/schema.json
+++ b/test/valid-data/string-literals-hack/schema.json
@@ -19,6 +19,12 @@
         "literalWithString": {
           "type": "string"
         },
+        "literalWithStringAndNull": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
         "literals": {
           "enum": [
             "foo",
@@ -95,6 +101,7 @@
         "stringWithNull",
         "literalWithNull",
         "literalWithString",
+        "literalWithStringAndNull",
         "withRef",
         "withRefWithString",
         "withHack",
diff --git a/test/vega-lite/schema.json b/test/vega-lite/schema.json
index a0a64b449..b5aef98f9 100644
--- a/test/vega-lite/schema.json
+++ b/test/vega-lite/schema.json
@@ -4428,46 +4428,37 @@
       ]
     },
     "BinnedTimeUnit": {
-      "anyOf": [
-        {
-          "enum": [
-            "binnedyear",
-            "binnedyearquarter",
-            "binnedyearquartermonth",
-            "binnedyearmonth",
-            "binnedyearmonthdate",
-            "binnedyearmonthdatehours",
-            "binnedyearmonthdatehoursminutes",
-            "binnedyearmonthdatehoursminutesseconds",
-            "binnedyearweek",
-            "binnedyearweekday",
-            "binnedyearweekdayhours",
-            "binnedyearweekdayhoursminutes",
-            "binnedyearweekdayhoursminutesseconds",
-            "binnedyeardayofyear"
-          ],
-          "type": "string"
-        },
-        {
-          "enum": [
-            "binnedutcyear",
-            "binnedutcyearquarter",
-            "binnedutcyearquartermonth",
-            "binnedutcyearmonth",
-            "binnedutcyearmonthdate",
-            "binnedutcyearmonthdatehours",
-            "binnedutcyearmonthdatehoursminutes",
-            "binnedutcyearmonthdatehoursminutesseconds",
-            "binnedutcyearweek",
-            "binnedutcyearweekday",
-            "binnedutcyearweekdayhours",
-            "binnedutcyearweekdayhoursminutes",
-            "binnedutcyearweekdayhoursminutesseconds",
-            "binnedutcyeardayofyear"
-          ],
-          "type": "string"
-        }
-      ]
+      "enum": [
+        "binnedyear",
+        "binnedyearquarter",
+        "binnedyearquartermonth",
+        "binnedyearmonth",
+        "binnedyearmonthdate",
+        "binnedyearmonthdatehours",
+        "binnedyearmonthdatehoursminutes",
+        "binnedyearmonthdatehoursminutesseconds",
+        "binnedyearweek",
+        "binnedyearweekday",
+        "binnedyearweekdayhours",
+        "binnedyearweekdayhoursminutes",
+        "binnedyearweekdayhoursminutesseconds",
+        "binnedyeardayofyear",
+        "binnedutcyear",
+        "binnedutcyearquarter",
+        "binnedutcyearquartermonth",
+        "binnedutcyearmonth",
+        "binnedutcyearmonthdate",
+        "binnedutcyearmonthdatehours",
+        "binnedutcyearmonthdatehoursminutes",
+        "binnedutcyearmonthdatehoursminutesseconds",
+        "binnedutcyearweek",
+        "binnedutcyearweekday",
+        "binnedutcyearweekdayhours",
+        "binnedutcyearweekdayhoursminutes",
+        "binnedutcyearweekdayhoursminutesseconds",
+        "binnedutcyeardayofyear"
+      ],
+      "type": "string"
     },
     "Blend": {
       "enum": [
@@ -19228,29 +19219,9 @@
       "type": "object"
     },
     "ParseValue": {
-      "anyOf": [
-        {
-          "type": "null"
-        },
-        {
-          "type": "string"
-        },
-        {
-          "const": "string",
-          "type": "string"
-        },
-        {
-          "const": "boolean",
-          "type": "string"
-        },
-        {
-          "const": "date",
-          "type": "string"
-        },
-        {
-          "const": "number",
-          "type": "string"
-        }
+      "type": [
+        "string",
+        "null"
       ]
     },
     "PivotTransform": {