diff --git a/packages/core/src/blocks/defaultBlockTypeGuards.ts b/packages/core/src/blocks/defaultBlockTypeGuards.ts
index 00bb122098..e9a4f8e9b5 100644
--- a/packages/core/src/blocks/defaultBlockTypeGuards.ts
+++ b/packages/core/src/blocks/defaultBlockTypeGuards.ts
@@ -50,7 +50,7 @@ export function editorHasBlockWithType<
     if (typeof propSpec === "string") {
       if (
         editor.schema.blockSpecs[blockType].config.propSchema[propName]
-          .default &&
+          .default !== undefined &&
         typeof editor.schema.blockSpecs[blockType].config.propSchema[propName]
           .default !== propSpec
       ) {
@@ -58,7 +58,8 @@ export function editorHasBlockWithType<
       }
 
       if (
-        editor.schema.blockSpecs[blockType].config.propSchema[propName].type &&
+        editor.schema.blockSpecs[blockType].config.propSchema[propName].type !==
+          undefined &&
         editor.schema.blockSpecs[blockType].config.propSchema[propName].type !==
           propSpec
       ) {
@@ -97,23 +98,11 @@ export function editorHasBlockWithType<
           .values === "object" &&
         typeof propSpec.values === "object"
       ) {
-        if (
-          editor.schema.blockSpecs[blockType].config.propSchema[propName].values
-            .length !== propSpec.values.length
-        ) {
-          return false;
-        }
-
-        for (
-          let i = 0;
-          i <
-          editor.schema.blockSpecs[blockType].config.propSchema[propName].values
-            .length;
-          i++
-        ) {
+        for (const value of propSpec.values) {
           if (
-            editor.schema.blockSpecs[blockType].config.propSchema[propName]
-              .values[i] !== propSpec.values[i]
+            !editor.schema.blockSpecs[blockType].config.propSchema[
+              propName
+            ].values.includes(value)
           ) {
             return false;
           }
diff --git a/tests/src/unit/core/typeGuards/runTests.test.ts b/tests/src/unit/core/typeGuards/runTests.test.ts
new file mode 100644
index 0000000000..a803e5f1e5
--- /dev/null
+++ b/tests/src/unit/core/typeGuards/runTests.test.ts
@@ -0,0 +1,135 @@
+import { BlockNoteEditor, editorHasBlockWithType } from "@blocknote/core";
+import { describe, expect, it } from "vitest";
+
+import { createTestEditor } from "../createTestEditor.js";
+import { testSchema } from "../testSchema.js";
+
+// Tests for verifying that type guards which check if an editor's schema
+// contains a block (and its props) are working correctly.
+describe("Editor block schema type guard tests", () => {
+  const getEditor = createTestEditor(testSchema) as () => BlockNoteEditor<
+    any,
+    any,
+    any
+  >;
+
+  it("blockType", () => {
+    expect(editorHasBlockWithType(getEditor(), "heading")).toBeTruthy();
+  });
+
+  it("blockTypeInvalid", () => {
+    expect(editorHasBlockWithType(getEditor(), "embed")).toBeFalsy();
+  });
+
+  it("blockWithPropTypes", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "heading", {
+        level: "number",
+        textColor: "string",
+      }),
+    ).toBeTruthy();
+  });
+
+  it("blockWithPropTypesInvalidType", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "heading", {
+        level: "number",
+        textColor: "number",
+      }),
+    ).toBeFalsy();
+  });
+
+  it("blockWithPropSchema", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "heading", {
+        level: { default: 1, values: [1, 2, 3] },
+        textColor: { default: "default" },
+      }),
+    ).toBeTruthy();
+  });
+
+  it("blockWithPropSchemaInvalidType", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "heading", {
+        level: { default: 1, values: [1, 2, 3] },
+        textColor: { default: 1 },
+      }),
+    ).toBeFalsy();
+  });
+
+  it("blockWithPropSchemaInvalidValues", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "heading", {
+        level: { default: 1, values: [1, 2, 3, 4, 5, 6, 7] },
+        textColor: { default: "default" },
+      }),
+    ).toBeFalsy();
+  });
+
+  it("blockWithPropTypesUndefinedDefault", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "numberedListItem", {
+        start: "number",
+        textColor: "string",
+      }),
+    ).toBeTruthy();
+  });
+
+  it("blockWithPropSchemaUndefinedDefaultInvalidType", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "numberedListItem", {
+        start: "string",
+        textColor: "string",
+      }),
+    ).toBeFalsy();
+  });
+
+  it("customBlockType", () => {
+    expect(editorHasBlockWithType(getEditor(), "simpleImage")).toBeTruthy();
+  });
+
+  it("customBlockWithPropTypes", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "simpleImage", {
+        name: "string",
+        url: "string",
+      }),
+    ).toBeTruthy();
+  });
+
+  it("customBlockWithPropTypesInvalidType", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "simpleImage", {
+        name: "string",
+        url: "number",
+      }),
+    ).toBeFalsy();
+  });
+
+  it("customBlockWithPropSchema", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "simpleImage", {
+        name: { default: "" },
+        url: { default: "" },
+      }),
+    ).toBeTruthy();
+  });
+
+  it("customBlockWithPropSchemaInvalidType", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "simpleImage", {
+        name: { default: false },
+        url: { default: "" },
+      }),
+    ).toBeFalsy();
+  });
+
+  it("customBlockWithPropSchemaInvalidValues", () => {
+    expect(
+      editorHasBlockWithType(getEditor(), "simpleImage", {
+        name: { default: "", values: ["image", "photo"] },
+        url: { default: "" },
+      }),
+    ).toBeFalsy();
+  });
+});