diff --git a/documentation/Makefile b/documentation/Makefile
index 87a6f8a8b..2df23ebf4 100644
--- a/documentation/Makefile
+++ b/documentation/Makefile
@@ -19,7 +19,7 @@ endif
 
 # Put it first so that "make" without argument is like "make help".
 help:
-	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
 
 .PHONY: all checks help Makefile clean stylecheck publish latexpdf
 
@@ -51,12 +51,10 @@ sphinx-lint:
 #   Unable to read an entire line---bufsize=200000. Please increase buf_size in texmf.cnf.
 latexpdf:
 	$(SOURCEDIR)/set_versions.py
-	buf_size=10000000 LATEXMKOPTS="-silent" $(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+	buf_size=10000000 LATEXMKOPTS="-silent" $(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
 
 all: html epub latexpdf
 
-# Catch-all target: route all unknown targets to Sphinx using the new
-# "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %:
 	$(SOURCEDIR)/set_versions.py
-	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)