diff --git a/inspector-vc/src/main/java/org/oneedtech/inspect/vc/probe/TypePropertyProbe.java b/inspector-vc/src/main/java/org/oneedtech/inspect/vc/probe/TypePropertyProbe.java
index 2c25d7d..7896617 100644
--- a/inspector-vc/src/main/java/org/oneedtech/inspect/vc/probe/TypePropertyProbe.java
+++ b/inspector-vc/src/main/java/org/oneedtech/inspect/vc/probe/TypePropertyProbe.java
@@ -33,8 +33,7 @@ public class TypePropertyProbe extends PropertyProbe {
 
 		List<String> allowedValues = expected.getAllowedTypeValues();
 		if (allowedValues.isEmpty()) {
-			// TODO implement
-			throw new IllegalStateException();
+			return fatal("The type property is invalid", ctx);
 		}
 		if (!values.stream().anyMatch(v -> allowedValues.contains(v))) {
 			return fatal(formatMessage(values), ctx);
diff --git a/inspector-vc/src/test/java/org/oneedtech/inspect/vc/OB20Tests.java b/inspector-vc/src/test/java/org/oneedtech/inspect/vc/OB20Tests.java
index 4325443..05f678f 100644
--- a/inspector-vc/src/test/java/org/oneedtech/inspect/vc/OB20Tests.java
+++ b/inspector-vc/src/test/java/org/oneedtech/inspect/vc/OB20Tests.java
@@ -17,6 +17,7 @@ import org.oneedtech.inspect.core.Inspector.Behavior;
 import org.oneedtech.inspect.core.report.Report;
 import org.oneedtech.inspect.test.PrintHelper;
 import org.oneedtech.inspect.vc.probe.ContextPropertyProbe;
+import org.oneedtech.inspect.vc.probe.TypePropertyProbe;
 import org.oneedtech.inspect.vc.util.TestOB20Inspector.TestBuilder;
 
 public class OB20Tests {
@@ -43,17 +44,6 @@ public class OB20Tests {
 		});
 	}
 
-	@Test
-	void testSimpleJsonInvalidContext() {
-		assertDoesNotThrow(()->{
-			Report report = validator.run(Samples.OB20.JSON.SIMPLE_ASSERTION_INVALID_CONTEXT_JSON.asFileResource());
-			if(verbose) PrintHelper.print(report, true);
-			assertInvalid(report);
-			assertFatalCount(report, 1);
-			assertHasProbeID(report, ContextPropertyProbe.ID, true);
-		});
-	}
-
 	@Test
 	void testSimplePNGPlainValid() {
 		assertDoesNotThrow(()->{
@@ -72,6 +62,28 @@ public class OB20Tests {
 		});
 	}
 
+	@Test
+	void testSimpleJsonInvalidContext() {
+		assertDoesNotThrow(()->{
+			Report report = validator.run(Samples.OB20.JSON.SIMPLE_ASSERTION_INVALID_CONTEXT_JSON.asFileResource());
+			if(verbose) PrintHelper.print(report, true);
+			assertInvalid(report);
+			assertFatalCount(report, 1);
+			assertHasProbeID(report, ContextPropertyProbe.ID, true);
+		});
+	}
+
+	@Test
+	void testSimpleJsonInvalidType() {
+		assertDoesNotThrow(()->{
+			Report report = validator.run(Samples.OB20.JSON.SIMPLE_ASSERTION_INVALID_TYPE_JSON.asFileResource());
+			if(verbose) PrintHelper.print(report, true);
+			assertInvalid(report);
+			assertFatalCount(report, 1);
+			assertHasProbeID(report, TypePropertyProbe.ID, true);
+		});
+	}
+
 
 
 	@Nested
diff --git a/inspector-vc/src/test/java/org/oneedtech/inspect/vc/Samples.java b/inspector-vc/src/test/java/org/oneedtech/inspect/vc/Samples.java
index c628249..6f3f861 100644
--- a/inspector-vc/src/test/java/org/oneedtech/inspect/vc/Samples.java
+++ b/inspector-vc/src/test/java/org/oneedtech/inspect/vc/Samples.java
@@ -46,6 +46,7 @@ public class Samples {
 			//  original: test_verify: test_verify_function
 			public final static Sample SIMPLE_ASSERTION_JSON = new Sample("ob20/basic-assertion.json", true);
 			public final static Sample SIMPLE_ASSERTION_INVALID_CONTEXT_JSON = new Sample("ob20/basic-assertion-invalid-context.json", true);
+			public final static Sample SIMPLE_ASSERTION_INVALID_TYPE_JSON = new Sample("ob20/basic-assertion-invalid-type.json", true);
 			// original: test_graph: test_verify_with_redirection
 			public final static Sample WARNING_REDIRECTION_ASSERTION_JSON = new Sample("ob20/warning-with-redirection.json", true);
 			// original: test_validation: test_can_input_badgeclass
diff --git a/inspector-vc/src/test/resources/ob20/basic-assertion-invalid-type.json b/inspector-vc/src/test/resources/ob20/basic-assertion-invalid-type.json
new file mode 100644
index 0000000..527cd67
--- /dev/null
+++ b/inspector-vc/src/test/resources/ob20/basic-assertion-invalid-type.json
@@ -0,0 +1,18 @@
+{
+  "@context": "https://w3id.org/openbadges/v2",
+  "type": "OtherAssertion",
+  "id": "https://example.org/beths-robotics-badge.json",
+  "recipient": {
+    "type": "email",
+    "hashed": true,
+    "salt": "deadsea",
+    "identity": "sha256$ecf5409f3f4b91ab60cc5ef4c02aef7032354375e70cf4d8e43f6a1d29891942"
+  },
+  "image": "https://example.org/beths-robot-badge.png",
+  "evidence": "https://example.org/beths-robot-work.html",
+  "issuedOn": "2016-12-31T23:59:59Z",
+  "badge": "https://example.org/robotics-badge.json",
+  "verification": {
+    "type": "hosted"
+  }
+}
\ No newline at end of file