diff --git a/src/csharp/Grpc.Tools.Tests/ProtoCompileCommandLineGeneratorTest.cs b/src/csharp/Grpc.Tools.Tests/ProtoCompileCommandLineGeneratorTest.cs
index e9efa78f96d..15b879141e0 100644
--- a/src/csharp/Grpc.Tools.Tests/ProtoCompileCommandLineGeneratorTest.cs
+++ b/src/csharp/Grpc.Tools.Tests/ProtoCompileCommandLineGeneratorTest.cs
@@ -245,7 +245,8 @@ namespace Grpc.Tools.Tests
                     else
                     {
                         // Ignore expected error
-                        if (e.Message != "\"protoc.exe\" exited with code -1.")
+                        // "protoc/protoc.exe" existed with code -1.
+                        if (!e.Message.EndsWith("exited with code -1."))
                         {
                             Assert.Fail($"Error logged by build engine:\n{e.Message}");
                         }