Basic testing.
diff --git a/grpc-build-system.bzl b/grpc-build-system.bzl
index 1d6d1a4..c18c57f 100644
--- a/grpc-build-system.bzl
+++ b/grpc-build-system.bzl
@@ -8,6 +8,7 @@
     hdrs = hdrs,
     deps = deps,
     copts = copts,
+    linkopts = ["-pthread"],
     includes = [
         "include"
     ]