diff --git a/http/bin/prune_blog b/http/bin/prune_blog
index 51be54a..849b293 100755
--- a/http/bin/prune_blog
+++ b/http/bin/prune_blog
@@ -18,19 +18,21 @@ do
   fi
 
   post_rel_path="$(echo "$post" | cut -c${#BLOG_DIR_IN_SRC}- | cut -c3-)"
-  post_basename="${post_rel_path::${#post_rel_path}-${#last_segment}-1}"
+  post_basename_len=$(( ${#post_rel_path} - ( ${#last_segment} + 1 ) ))
+  post_basename="$(echo "${post_rel_path}" | cut -c1-${post_basename_len})"
 	post_src="${BLOGS}/${BLOG}/${post_basename}.${BLOG_EXT}"
 	if [ -f "$post_src" ]
 	then
     continue
 	fi
 
-	penultimate_segment="${post::${#post}-${#last_segment}-1}"
+  penultimate_segment_len=$(( ${#post} - ( ${#last_segment} + 1 ) ))
+  penultimate_segment="$(echo "${post}" | cut -c1-${penultimate_segment_len})"
   penultimate_segment="${penultimate_segment##*\.}"
-  post_basename="${post_rel_path::${#post_rel_path}-${#last_segment}-${#penultimate_segment}-2}"
+  post_basename_len=$(( ${#post_rel_path} - ( ${#last_segment} + ${#penultimate_segment} + 2 ) ))
+  post_basename="$(echo "${post_rel_path}" | cut -c1-${post_basename_len})"
   if [ -f "${LAYOUTS}/${penultimate_segment}.layout.${last_segment}" ]
   then
-    post_basename="${post_rel_path::${#post_rel_path}-${#last_segment}-${#penultimate_segment}-2}"
   	post_src="${BLOGS}/${BLOG}/${post_basename}.${BLOG_EXT}"
    	if [ -f "$post_src" ]
    	then