diff --git a/azurelinuxagent/common/osutil/default.py b/azurelinuxagent/common/osutil/default.py
index 584515dc6..746c43633 100644
--- a/azurelinuxagent/common/osutil/default.py
+++ b/azurelinuxagent/common/osutil/default.py
@@ -346,7 +346,7 @@ def deploy_ssh_pubkey(self, username, pubkey):
                 raise OSUtilError("Bad public key: {0}".format(value))
             if not value.endswith("\n"):
                 value += "\n"
-            fileutil.write_file(path, value)
+            fileutil.write_file(path, value, append=True)
         elif thumbprint is not None:
             lib_dir = conf.get_lib_dir()
             crt_path = os.path.join(lib_dir, thumbprint + '.crt')