diff --git a/mdbooker.awk b/mdbooker.awk
index 507c430..3e83cc9 100644
--- a/mdbooker.awk
+++ b/mdbooker.awk
@@ -1,4 +1,5 @@
 BEGIN {
+  Base = ENVIRON["BASE"]
   printf "" > (SUMMARY = (BOOK = "book/") "SUMMARY.md")
   H = 0
   Title = Content = ""
@@ -35,8 +36,12 @@ function pass2(   l,f,t) {
       handleTitle(RLENGTH, 2)
     else {
       if (match(l = $0, /]\(#[^)]+\)/)) {
-        print "  fix link: #" (f=substr(l, RSTART + 3, RLENGTH - 4)) " -> " (t = Link2Path[f])
+        print "  fix link: #" (f = substr(l, RSTART + 3, RLENGTH - 4)) " -> " (t = Link2Path[f])
         l = substr(l, 1, RSTART - 1) "](" t ")" substr(l, RSTART + RLENGTH)
+      } else if (match(l,/]\([^)]+\)/) && (f = substr(l, RSTART + 2, RLENGTH - 3)) !~ /https?:/) {
+        print "  fix link: " f " -> " (t = Base f)
+        l = substr(l, 1, RSTART - 1) "](" t ")" substr(l, RSTART + RLENGTH)
+        print ">>" l
       }
       Content = Content "\n" l
     }