diff --git a/src/value.js b/src/value.js
index 1ae90fed..445f28be 100644
--- a/src/value.js
+++ b/src/value.js
@@ -1,41 +1,10 @@
 import { camelToDash } from "./utils.js";
 
 const setters = {
-  string: (host, value, attrName) => {
-    const nextValue = value ? String(value) : "";
-    if (nextValue) {
-      host.setAttribute(attrName, nextValue);
-    } else {
-      host.removeAttribute(attrName);
-    }
-
-    return nextValue;
-  },
-  number: (host, value, attrName) => {
-    const nextValue = Number(value);
-    host.setAttribute(attrName, nextValue);
-    return nextValue;
-  },
-  boolean: (host, value, attrName) => {
-    const nextValue = Boolean(value);
-    if (nextValue) {
-      host.setAttribute(attrName, "");
-    } else {
-      host.removeAttribute(attrName);
-    }
-    return nextValue;
-  },
-  undefined: (host, value, attrName) => {
-    const type = typeof value;
-    const set = type !== "undefined" && setters[type];
-    if (set) {
-      return set(host, value, attrName);
-    } else if (host.hasAttribute(attrName)) {
-      host.removeAttribute(attrName);
-    }
-
-    return value;
-  },
+  string: String,
+  number: Number,
+  boolean: Boolean,
+  undefined: (value) => value,
 };
 
 export default function value(key, desc) {
@@ -50,19 +19,26 @@ export default function value(key, desc) {
 
   const attrName = camelToDash(key);
 
+  function reflect(host, value) {
+    if (!value && value !== 0) {
+      host.removeAttribute(attrName);
+    } else {
+      host.setAttribute(attrName, value === true ? "" : value);
+    }
+  }
+
   return {
     get: (host, value) => (value === undefined ? desc.value : value),
-    set: (host, value) => set(host, value, attrName),
-    connect:
-      type !== "undefined"
-        ? (host, key, invalidate) => {
-            if (!host.hasAttribute(attrName) && host[key] === desc.value) {
-              host[key] = set(host, desc.value, attrName);
+    set: (host, value) => set(value),
+    connect: desc.connect,
+    observe:
+      type === "undefined"
+        ? desc.observe
+        : desc.observe
+          ? (host, value, lastValue) => {
+              reflect(host, value);
+              desc.observe(host, value, lastValue);
             }
-
-            return desc.connect && desc.connect(host, key, invalidate);
-          }
-        : desc.connect,
-    observe: desc.observe,
+          : reflect,
   };
 }
diff --git a/test/spec/define.js b/test/spec/define.js
index 4b0a337c..72ab48df 100644
--- a/test/spec/define.js
+++ b/test/spec/define.js
@@ -316,7 +316,7 @@ describe("define:", () => {
         expect(el.getAttribute("prop1")).toBe("a");
         expect(el.getAttribute("prop2")).toBe("1");
         expect(el.getAttribute("prop3")).toBe("");
-        expect(el.getAttribute("not-defined")).toBe("abc");
+        expect(el.getAttribute("not-defined")).toBe(null);
       });
     });