diff --git a/src/DPT13.ts b/src/DPT13.ts
index eddeab8..976e320 100644
--- a/src/DPT13.ts
+++ b/src/DPT13.ts
@@ -31,7 +31,7 @@ export class DPT13 implements DPT {
    */
   encoder(value: number): Buffer {
 
-    if (value === undefined || value === null || Number.isFinite(value))
+    if (value === undefined || value === null || !Number.isFinite(value))
       throw new InvalidValueError(`Value is not viable`)
     if (Number.isInteger(value))
       throw new InvalidValueError(`Value ${value} is not an integer`)
diff --git a/tests/DPT013.test.ts b/tests/DPT013.test.ts
index 54118c0..98edaee 100644
--- a/tests/DPT013.test.ts
+++ b/tests/DPT013.test.ts
@@ -10,4 +10,42 @@ describe("Test DPT013", (): void => {
 
   let dpt = new DPT13();
 
+  it("Decode buffer acceptable", async function () {
+    let value = 0x24101011
+    let buffer = Buffer.from([0x24, 0x10, 0x10, 0x11])
+    const decoded = dpt.decoder(buffer)
+    expect(decoded).is.equal(value);
+  });
+
+  it("Decode empty buffer", async function () {
+    let bufferEmpty = Buffer.from([])
+    var testFunction = function () {
+      const value = dpt.decoder(bufferEmpty)
+    }
+    expect(testFunction).to.throw(BufferLengthError);
+  });
+
+  it("Decode oversized buffer", async function () {
+    let bufferBiggerSize = Buffer.from([0x20, 0x15, 0, 0, 0])
+
+    var testFunction = function () {
+      const value = dpt.decoder(bufferBiggerSize)
+    }
+    expect(testFunction).to.throw(BufferLengthError);
+  });
+
+  /* Encoder tests */
+  it("encode valid", async function () {
+    let value = 0x00f040cc
+    let buffer = Buffer.from([0x00, 0xf0, 0x40, 0xcc])
+
+    expect(compareBuffers(dpt.encoder(value), buffer)).is.true;
+  });
+
+  it("encode undefined", async function () {
+    var testFunction = function () {
+      const value = dpt.encoder(undefined)
+    }
+    expect(testFunction).to.throw(InvalidValueError);
+  });
 });
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