diff --git a/build_tools/circle/build_doc.sh b/build_tools/circle/build_doc.sh
index c3481bd6c58c1..59c0fe659a2ad 100755
--- a/build_tools/circle/build_doc.sh
+++ b/build_tools/circle/build_doc.sh
@@ -79,7 +79,7 @@ get_build_type() {
         auto_example_files="$(echo "$img_fig_lines" | grep auto_examples | awk -F "/" '{print $NF}')"
 
         # remove "sphx_glr_" from path and accept replace _(\d\d\d|thumb).png with .py
-        scripts_names="$(echo "$auto_example_files" | sed 's/sphx_glr_//' | sed -e 's/_([[:digit:]][[:digit:]][[:digit:]]|thumb).png/.py/')"
+        scripts_names="$(echo "$auto_example_files" | sed 's/sphx_glr_//' | sed -E 's/_([[:digit:]][[:digit:]][[:digit:]]|thumb).png/.py/')"
 
         # get unique values
         examples_in_rst="$(echo "$scripts_names" | uniq )"