diff --git a/lib/jasmine-core/jasmine.js b/lib/jasmine-core/jasmine.js
index e55f611f..3c046ce9 100644
--- a/lib/jasmine-core/jasmine.js
+++ b/lib/jasmine-core/jasmine.js
@@ -769,6 +769,14 @@ getJasmineRequireObj().util = function(j$) {
     }
   };
 
+  util.assertStructuredCloneable = function(v, msgPrefix) {
+    try {
+      structuredClone(v);
+    } catch (e) {
+      throw new Error(`${msgPrefix} can't be cloned`, { cause: e });
+    }
+  };
+
   return util;
 };
 
@@ -844,8 +852,12 @@ getJasmineRequireObj().Spec = function(j$) {
       return this.result.properties[key];
     }
 
-    // TODO: throw if the key or value is not structred cloneable
     setSpecProperty(key, value) {
+      // Key and value will eventually be cloned during reporting. The error
+      // thrown at that point if they aren't cloneable isn't very helpful.
+      // Throw a better one now.
+      j$.util.assertStructuredCloneable(key, 'Key');
+      j$.util.assertStructuredCloneable(value, 'Value');
       this.result.properties = this.result.properties || {};
       this.result.properties[key] = value;
     }
@@ -10604,6 +10616,11 @@ getJasmineRequireObj().Suite = function(j$) {
     }
 
     setSuiteProperty(key, value) {
+      // Key and value will eventually be cloned during reporting. The error
+      // thrown at that point if they aren't cloneable isn't very helpful.
+      // Throw a better one now.
+      j$.util.assertStructuredCloneable(key, 'Key');
+      j$.util.assertStructuredCloneable(value, 'Value');
       this.result.properties = this.result.properties || {};
       this.result.properties[key] = value;
     }
diff --git a/spec/core/SpecSpec.js b/spec/core/SpecSpec.js
index 5d727729..18769efa 100644
--- a/spec/core/SpecSpec.js
+++ b/spec/core/SpecSpec.js
@@ -102,6 +102,26 @@ describe('Spec', function() {
         b: 'original-value'
       });
     });
+
+    it('throws if the key is not structured-cloneable', function() {
+      const spec = new jasmineUnderTest.Spec({
+        queueableFn: { fn: () => {} }
+      });
+
+      expect(function() {
+        spec.setSpecProperty(new Promise(() => {}), '');
+      }).toThrowError("Key can't be cloned");
+    });
+
+    it('throws if the value is not structured-cloneable', function() {
+      const spec = new jasmineUnderTest.Spec({
+        queueableFn: { fn: () => {} }
+      });
+
+      expect(function() {
+        spec.setSpecProperty('k', new Promise(() => {}));
+      }).toThrowError("Value can't be cloned");
+    });
   });
 
   describe('status', function() {
diff --git a/spec/core/SuiteSpec.js b/spec/core/SuiteSpec.js
index af2e4d64..e3961193 100644
--- a/spec/core/SuiteSpec.js
+++ b/spec/core/SuiteSpec.js
@@ -405,4 +405,22 @@ describe('Suite', function() {
       expect(subject.hasChildWithDescription('a spec')).toBeFalse();
     });
   });
+
+  describe('#setSuiteProperty', function() {
+    it('throws if the key is not structured-cloneable', function() {
+      const suite = new jasmineUnderTest.Suite({});
+
+      expect(function() {
+        suite.setSuiteProperty(new Promise(() => {}), '');
+      }).toThrowError("Key can't be cloned");
+    });
+
+    it('throws if the value is not structured-cloneable', function() {
+      const suite = new jasmineUnderTest.Suite({});
+
+      expect(function() {
+        suite.setSuiteProperty('k', new Promise(() => {}));
+      }).toThrowError("Value can't be cloned");
+    });
+  });
 });
diff --git a/src/core/Spec.js b/src/core/Spec.js
index 05383d93..56d572bf 100644
--- a/src/core/Spec.js
+++ b/src/core/Spec.js
@@ -70,8 +70,12 @@ getJasmineRequireObj().Spec = function(j$) {
       return this.result.properties[key];
     }
 
-    // TODO: throw if the key or value is not structred cloneable
     setSpecProperty(key, value) {
+      // Key and value will eventually be cloned during reporting. The error
+      // thrown at that point if they aren't cloneable isn't very helpful.
+      // Throw a better one now.
+      j$.util.assertStructuredCloneable(key, 'Key');
+      j$.util.assertStructuredCloneable(value, 'Value');
       this.result.properties = this.result.properties || {};
       this.result.properties[key] = value;
     }
diff --git a/src/core/Suite.js b/src/core/Suite.js
index 58e226f4..4a75565f 100644
--- a/src/core/Suite.js
+++ b/src/core/Suite.js
@@ -31,6 +31,11 @@ getJasmineRequireObj().Suite = function(j$) {
     }
 
     setSuiteProperty(key, value) {
+      // Key and value will eventually be cloned during reporting. The error
+      // thrown at that point if they aren't cloneable isn't very helpful.
+      // Throw a better one now.
+      j$.util.assertStructuredCloneable(key, 'Key');
+      j$.util.assertStructuredCloneable(value, 'Value');
       this.result.properties = this.result.properties || {};
       this.result.properties[key] = value;
     }
diff --git a/src/core/util.js b/src/core/util.js
index e40d6a0e..f824df1d 100644
--- a/src/core/util.js
+++ b/src/core/util.js
@@ -80,5 +80,13 @@ getJasmineRequireObj().util = function(j$) {
     }
   };
 
+  util.assertStructuredCloneable = function(v, msgPrefix) {
+    try {
+      structuredClone(v);
+    } catch (e) {
+      throw new Error(`${msgPrefix} can't be cloned`, { cause: e });
+    }
+  };
+
   return util;
 };