diff --git a/var/spack/repos/builtin/packages/py-protobuf/package.py b/var/spack/repos/builtin/packages/py-protobuf/package.py
index 4876832dcf6..7cacda04161 100644
--- a/var/spack/repos/builtin/packages/py-protobuf/package.py
+++ b/var/spack/repos/builtin/packages/py-protobuf/package.py
@@ -57,6 +57,11 @@ def build_directory(self):
         else:
             return '.'
 
+    @when('+cpp')
+    def setup_build_environment(self, env):
+        protobuf_dir = self.spec['protobuf'].libs.directories[0]
+        env.prepend_path('LIBRARY_PATH', protobuf_dir)
+
     @when('+cpp')
     def build_args(self, spec, prefix):
         return ['--cpp_implementation']