diff --git a/build-docs b/build-docs
index e7058360..42fe3866 100755
--- a/build-docs
+++ b/build-docs
@@ -105,7 +105,7 @@ function build_source {
 
     # preprocess markdown to add implicit figures
     sed -E \
-    -e 's|^!\[(.+)]\([ ]*(.+)[ ]*"(.+)"[ ]*\)$|<figure><a href="\2"><img src="\2" alt="\1" /></a><figcaption>\3</figcaption></figure>|' \
+    -e 's|^!\[(.+)]\([ ]*([^ ]+)[ ]*"(.+)"[ ]*\)$|<figure><a href="\2"><img src="\2" alt="\1" /></a><figcaption>\3</figcaption></figure>|' \
     -i.sedbak "${SOURCE}"
     # convert preprocessed markdown document to html
     "${MARKDOWN}" -fdlextra -ffencedcode -ffootnote -fgithubtags "${SOURCE}" > "${DOCUMENT_Content}"