diff --git a/BrowserStackLocal/BrowserStackLocal Unit Tests/BrowserStackTunnelTests.cs b/BrowserStackLocal/BrowserStackLocal Unit Tests/BrowserStackTunnelTests.cs
index 8c83b0a..c33314d 100644
--- a/BrowserStackLocal/BrowserStackLocal Unit Tests/BrowserStackTunnelTests.cs	
+++ b/BrowserStackLocal/BrowserStackLocal Unit Tests/BrowserStackTunnelTests.cs	
@@ -133,6 +133,13 @@ public void testFallbackException()
     public class TunnelClass : BrowserStackTunnel
     {
       public TunnelClass() : base("test-user-agent") {}
+      // Stub the network boundary so these binary-path/fallback unit tests exercise
+      // the real path-resolution logic without making a live HTTP call to the
+      // endpoint API (which addBinaryPath triggers on first invocation).
+      protected override string fetchSourceUrl(string accessKey)
+      {
+        return null;
+      }
       public StringBuilder getOutputBuilder()
       {
         return output;
diff --git a/BrowserStackLocal/BrowserStackLocal Unit Tests/LocalTests.cs b/BrowserStackLocal/BrowserStackLocal Unit Tests/LocalTests.cs
index 918afa9..45d9ba2 100644
--- a/BrowserStackLocal/BrowserStackLocal Unit Tests/LocalTests.cs	
+++ b/BrowserStackLocal/BrowserStackLocal Unit Tests/LocalTests.cs	
@@ -107,7 +107,7 @@ public void TestWorksForBinaryPath()
       tunnelMock.Setup(mock => mock.Run("dummyKey", "", logAbsolute, "start"));
       local.setTunnel(tunnelMock.Object);
       local.start(options);
-      tunnelMock.Verify(mock => mock.addBinaryPath("dummyPath", "", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
+      tunnelMock.Verify(mock => mock.addBinaryPath("dummyPath", "dummyKey", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
       tunnelMock.Verify(mock => mock.addBinaryArguments(It.IsRegex("-logFile \"" + logAbsolute + "\" .*")), Times.Once());
       tunnelMock.Verify(mock => mock.Run("dummyKey", "", logAbsolute, "start"), Times.Once());
       local.stop();
@@ -129,7 +129,7 @@ public void TestWorksWithBooleanOptions()
       tunnelMock.Setup(mock => mock.Run("dummyKey", "", logAbsolute, "start"));
       local.setTunnel(tunnelMock.Object);
       local.start(options);
-      tunnelMock.Verify(mock => mock.addBinaryPath("", "", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
+      tunnelMock.Verify(mock => mock.addBinaryPath("", "dummyKey", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
       tunnelMock.Verify(mock => mock.addBinaryArguments(It.IsRegex("-vvv.*-force.*-forcelocal.*-forceproxy.*-onlyAutomate.*")), Times.Once());
       tunnelMock.Verify(mock => mock.Run("dummyKey", "", logAbsolute, "start"), Times.Once());
       local.stop();
@@ -152,7 +152,7 @@ public void TestWorksWithValueOptions()
       tunnelMock.Setup(mock =>mock.Run("dummyKey", "", logAbsolute, "start"));
       local.setTunnel(tunnelMock.Object);
       local.start(options);
-      tunnelMock.Verify(mock => mock.addBinaryPath("", "", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
+      tunnelMock.Verify(mock => mock.addBinaryPath("", "dummyKey", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
       tunnelMock.Verify(mock => mock.addBinaryArguments(
         It.IsRegex("-localIdentifier.*dummyIdentifier.*dummyHost.*-proxyHost.*dummyHost.*-proxyPort.*dummyPort.*-proxyUser.*dummyUser.*-proxyPass.*dummyPass.*")
         ), Times.Once());
@@ -175,7 +175,7 @@ public void TestWorksWithCustomOptions()
       tunnelMock.Setup(mock => mock.Run("dummyKey", "", logAbsolute, "start"));
       local.setTunnel(tunnelMock.Object);
       local.start(options);
-      tunnelMock.Verify(mock => mock.addBinaryPath("", "", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
+      tunnelMock.Verify(mock => mock.addBinaryPath("", "dummyKey", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
       tunnelMock.Verify(mock => mock.addBinaryArguments(
         It.IsRegex("-customBoolKey1.*-customBoolKey2.*-customKey1.*customValue1.*-customKey2.*customValue2.*")
         ), Times.Once());
@@ -200,7 +200,7 @@ public void TestCallsFallbackOnFailure()
       });
       local.setTunnel(tunnelMock.Object);
       local.start(options);
-      tunnelMock.Verify(mock => mock.addBinaryPath("", "", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
+      tunnelMock.Verify(mock => mock.addBinaryPath("", "dummyKey", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
       tunnelMock.Verify(mock => mock.addBinaryArguments(It.IsRegex("-logFile \"" + logAbsolute + "\" .*")), Times.Once());
       tunnelMock.Verify(mock => mock.Run("dummyKey", "", logAbsolute, "start"), Times.Exactly(2));
       tunnelMock.Verify(mock => mock.fallbackPaths(), Times.Once());
@@ -219,7 +219,7 @@ public void TestKillsTunnel()
       local.setTunnel(tunnelMock.Object);
       local.start(options);
       local.stop();
-      tunnelMock.Verify(mock => mock.addBinaryPath("", "", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
+      tunnelMock.Verify(mock => mock.addBinaryPath("", "dummyKey", It.IsAny<bool>(), It.IsAny<Exception>()), Times.Once);
       tunnelMock.Verify(mock => mock.addBinaryArguments(It.IsRegex("-logFile \"" + logAbsolute + "\" .*")), Times.Once());
       tunnelMock.Verify(mock => mock.Run("dummyKey", "", logAbsolute, "start"), Times.Once());
     }
diff --git a/BrowserStackLocal/BrowserStackLocal/BrowserStackTunnel.cs b/BrowserStackLocal/BrowserStackLocal/BrowserStackTunnel.cs
index f825c29..911d47b 100644
--- a/BrowserStackLocal/BrowserStackLocal/BrowserStackTunnel.cs
+++ b/BrowserStackLocal/BrowserStackLocal/BrowserStackTunnel.cs
@@ -184,7 +184,7 @@ public void modifyBinaryPermission()
       }
     }
 
-    private string fetchSourceUrl(string accessKey)
+    protected virtual string fetchSourceUrl(string accessKey)
     {
       var url = "https://local.browserstack.com/binary/api/v1/endpoint";