diff --git a/lib/spack/docs/conf.py b/lib/spack/docs/conf.py
index 48f1fda47e5..d1248485427 100644
--- a/lib/spack/docs/conf.py
+++ b/lib/spack/docs/conf.py
@@ -103,7 +103,7 @@
 # Without this, the API Docs will never actually update
 #
 apidoc_args = [
-    'sphinx_apidoc',   # The first arugment is ignored
+    '--force',         # Older versions of Sphinx ignore the first argument
     '--force',         # Overwrite existing files
     '--no-toc',        # Don't create a table of contents file
     '--output-dir=.',  # Directory to place all output