diff --git a/packages/zipkin-instrumentation-grpc/README.md b/packages/zipkin-instrumentation-grpc/README.md
index 104a74e6..2c865edc 100644
--- a/packages/zipkin-instrumentation-grpc/README.md
+++ b/packages/zipkin-instrumentation-grpc/README.md
@@ -1,5 +1,6 @@
-# zipkin-instrumentation-grpc
+# zipkin-instrumentation-grpc-wrd
 
+This lib contains just a bugfix for the sample flag on the library created by @lnshi's: zipkin-instrumentation-grpc.
 This lib is the interceptor for [Zipkin](https://github.com/openzipkin/zipkin) to intercept your [GRPC](https://github.com/grpc/grpc) calls(unary/stream).
 
 ## Project test status
@@ -138,6 +139,3 @@ This lib is the interceptor for [Zipkin](https://github.com/openzipkin/zipkin) t
   }
   ```
 
-## Maintainer
-
-Feel free to `@lnshi` on Github for any issue of this lib 🙂
diff --git a/packages/zipkin-instrumentation-grpc/package.json b/packages/zipkin-instrumentation-grpc/package.json
index f436db13..14a18d87 100644
--- a/packages/zipkin-instrumentation-grpc/package.json
+++ b/packages/zipkin-instrumentation-grpc/package.json
@@ -1,6 +1,6 @@
 {
-  "name": "zipkin-instrumentation-grpc",
-  "version": "0.0.6",
+  "name": "zipkin-instrumentation-grpc-wrd",
+  "version": "0.0.1",
   "description": "Interceptor for instrumenting GRPC calls.",
   "main": "lib/index.js",
   "scripts": {
diff --git a/packages/zipkin-instrumentation-grpc/src/ZipkinGrpcInterceptor.js b/packages/zipkin-instrumentation-grpc/src/ZipkinGrpcInterceptor.js
index 3554ea4a..cb9563e1 100644
--- a/packages/zipkin-instrumentation-grpc/src/ZipkinGrpcInterceptor.js
+++ b/packages/zipkin-instrumentation-grpc/src/ZipkinGrpcInterceptor.js
@@ -3,7 +3,7 @@ const grpc = require('grpc');
 const {
   TraceId,
   Annotation,
-  option: {Some}
+  option: {Some, None}
 } = require('zipkin');
 
 class ZipkinGrpcInterceptor {
@@ -61,16 +61,11 @@ class ZipkinGrpcInterceptor {
       return;
     }
 
-    let ctxSampled = grpcMetadataFromIncomingCtx.get('x-b3-sampled')[0];
-    if (!(ctxSampled in ['0', '1'])) {
-      ctxSampled = '0';
-    }
-
     const ctxTraceInfo = new TraceId({
       traceId: new Some(ctxTraceId),
       parentId: new Some(ctxParentId),
       spanId: ctxSpanId,
-      sampled: new Some(ctxSampled)
+      sampled: ZipkinGrpcInterceptor._determineSampledValue(grpcMetadataFromIncomingCtx.get('x-b3-sampled')[0])
     });
 
     this.tracer.scoped(() => {
@@ -100,6 +95,12 @@ class ZipkinGrpcInterceptor {
     });
   }
 
+  static _determineSampledValue(ctxSampledAsString) {
+    if (!ctxSampledAsString) {
+      return None;
+    }
+    return new Some(ctxSampledAsString === '1' || ctxSampledAsString === 'true');
+  }
 }
 
 module.exports = ZipkinGrpcInterceptor;
diff --git a/packages/zipkin-instrumentation-grpc/test/integrationTest.js b/packages/zipkin-instrumentation-grpc/test/integrationTest.js
index 95a1ac94..f5b9721e 100644
--- a/packages/zipkin-instrumentation-grpc/test/integrationTest.js
+++ b/packages/zipkin-instrumentation-grpc/test/integrationTest.js
@@ -4,7 +4,7 @@ const zipkinBaseUrl = 'http://faked:64800';
 
 const CLSContext = require('zipkin-context-cls');
 
-const {Tracer, BatchRecorder} = require('zipkin');
+const {Tracer, BatchRecorder, option: {Some, None}} = require('zipkin');
 const {HttpLogger} = require('zipkin-transport-http');
 
 const recorder = new BatchRecorder({
@@ -53,4 +53,77 @@ describe('Zipkin GRPC interceptor basic test', () => {
 
     done();
   });
+
+  it("Pass in 'grpc.Metadata' with no sampled value, should set sampled to None", (done) => {
+    const metadata = new grpc.Metadata();
+    metadata.add('x-b3-traceid', '1AAA');
+    metadata.add('x-b3-parentspanid', '1BBB');
+    metadata.add('x-b3-spanid', '1CCC');
+
+    ZIPKIN_GRPC_INTCP.uponServerRecvGrpcCall({ serviceName: 'test-service1', grpcMetadataFromIncomingCtx: metadata});
+    expect(ZIPKIN_GRPC_INTCP.traceId.traceId).to.equal('1AAA');
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled).to.equal(None);
+
+    done();
+  });
+
+  it("Pass in 'grpc.Metadata' with sampled '0', should set sampled to Some(false)", (done) => {
+    const metadata = new grpc.Metadata();
+    metadata.add('x-b3-traceid', '2AAA');
+    metadata.add('x-b3-parentspanid', '2BBB');
+    metadata.add('x-b3-spanid', '2CCC');
+    metadata.add('x-b3-sampled', '0');
+
+    ZIPKIN_GRPC_INTCP.uponServerRecvGrpcCall({ serviceName: 'test-service2', grpcMetadataFromIncomingCtx: metadata});
+    expect(ZIPKIN_GRPC_INTCP.traceId.traceId).to.equal('2AAA');
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled).to.be.instanceOf(Some);
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled.value).to.equal(false);
+
+    done();
+  });
+
+  it("Pass in 'grpc.Metadata' with sampled '1', should set sampled to Some(true)", (done) => {
+    const metadata = new grpc.Metadata();
+    metadata.add('x-b3-traceid', '3AAA');
+    metadata.add('x-b3-parentspanid', '3BBB');
+    metadata.add('x-b3-spanid', '3CCC');
+    metadata.add('x-b3-sampled', '1');
+
+    ZIPKIN_GRPC_INTCP.uponServerRecvGrpcCall({ serviceName: 'test-service3', grpcMetadataFromIncomingCtx: metadata});
+    expect(ZIPKIN_GRPC_INTCP.traceId.traceId).to.equal('3AAA');
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled).to.be.instanceOf(Some);
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled.value).to.equal(true);
+
+    done();
+  });
+
+  it("Pass in 'grpc.Metadata' with sampled 'false', should set sampled to Some(false)", (done) => {
+    const metadata = new grpc.Metadata();
+    metadata.add('x-b3-traceid', '4AAA');
+    metadata.add('x-b3-parentspanid', '4BBB');
+    metadata.add('x-b3-spanid', '4CCC');
+    metadata.add('x-b3-sampled', 'false');
+
+    ZIPKIN_GRPC_INTCP.uponServerRecvGrpcCall({ serviceName: 'test-service4', grpcMetadataFromIncomingCtx: metadata});
+    expect(ZIPKIN_GRPC_INTCP.traceId.traceId).to.equal('4AAA');
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled).to.be.instanceOf(Some);
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled.value).to.equal(false);
+
+    done();
+  });
+
+  it("Pass in 'grpc.Metadata' with sampled 'true', should set sampled to Some(true)", (done) => {
+    const metadata = new grpc.Metadata();
+    metadata.add('x-b3-traceid', '5AAA');
+    metadata.add('x-b3-parentspanid', '5BBB');
+    metadata.add('x-b3-spanid', '5CCC');
+    metadata.add('x-b3-sampled', 'true');
+
+    ZIPKIN_GRPC_INTCP.uponServerRecvGrpcCall({ serviceName: 'test-service5', grpcMetadataFromIncomingCtx: metadata});
+    expect(ZIPKIN_GRPC_INTCP.traceId.traceId).to.equal('5AAA');
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled).to.be.instanceOf(Some);
+    expect(ZIPKIN_GRPC_INTCP.traceId.sampled.value).to.equal(true);
+
+    done();
+  });
 });