diff --git a/configure b/configure
index 1986e666..98f5f1ea 100755
--- a/configure
+++ b/configure
@@ -1551,16 +1551,16 @@ NOTMUCH_HAVE_PYTHON3_PYTEST=${have_python3_pytest}
 PLATFORM=${platform}
 EOF
 
-cat > sphinx.config <<EOF
-# Generated by configure, run from doc/conf.py
-EOF
-if [ $WITH_EMACS = "1" ]; then
-    printf "tags.add('WITH_EMACS')\n" >> sphinx.config
-fi
-if [ $WITH_PYTHON_DOCS = "1" ]; then
-    printf "tags.add('WITH_PYTHON')\n" >> sphinx.config
-fi
-printf "rsti_dir = '%s'\n" $(realpath emacs) >> sphinx.config
+{
+    echo "# Generated by configure, run from doc/conf.py"
+    if [ $WITH_EMACS = "1" ]; then
+        echo "tags.add('WITH_EMACS')"
+    fi
+    if [ $WITH_PYTHON_DOCS = "1" ]; then
+        echo "tags.add('WITH_PYTHON')"
+    fi
+    printf "rsti_dir = '%s'\n" $(realpath emacs)
+} > sphinx.config
 
 # Finally, after everything configured, inform the user how to continue.
 cat <<EOF