diff --git a/support/install.pl b/support/install.pl
index 9bcb486183..7106f5e5c3 100644
--- a/support/install.pl
+++ b/support/install.pl
@@ -316,7 +316,7 @@ sub rel_symlink {
    my $rel_link = $link;
    my $common_prefix = 1;
    while ($rel_link =~ s{^(/[^/]+)(?=/)}{}) {
-      if ($common_prefix && substr($target, 0, length($1)) eq $1) {
+      if ($common_prefix && substr($target, 0, length($1)+1) eq "$1/") {
          $target = substr($target, length($1));
       } else {
          $common_prefix = 0;