diff --git a/var/spack/repos/builtin/packages/xpmem/package.py b/var/spack/repos/builtin/packages/xpmem/package.py
index 0a47a65e6c5..05881090bd9 100644
--- a/var/spack/repos/builtin/packages/xpmem/package.py
+++ b/var/spack/repos/builtin/packages/xpmem/package.py
@@ -88,7 +88,7 @@ def configure_args(self):
         if "~kernel-module" in self.spec:
             # The kernel module is enabled by default. An attempt of explicit
             # enabling with '--enable-kernel-module' disables the module.
-            args.extend("--disable-kernel-module")
+            args.append("--disable-kernel-module")
 
         if self.spec.satisfies("@:2.6.5"):
             fmt = self.spec.format