diff --git a/devel/autoconf/Portfile b/devel/autoconf/Portfile
index c04b68be352b..61ac47d8e4a6 100644
--- a/devel/autoconf/Portfile
+++ b/devel/autoconf/Portfile
@@ -44,9 +44,17 @@ post-patch {
     touch ${worksrcpath}/man/autoreconf.1
 }
 
-# It should be safe to use the system Perl, since the scripts only use
-# core modules. The README prescribes 5.6 or later, and Tiger has 5.8.6.
-configure.perl      /usr/bin/perl
+if {${os.platform} eq "darwin"} {
+    # It should be safe to use the system Perl, since the scripts only use
+    # core modules. The README prescribes 5.6 or later, and Tiger has 5.8.6.
+    configure.perl  /usr/bin/perl
+} else {
+    depends_build-append \
+                    port:help2man \
+                    port:perl5
+    # https://trac.macports.org/ticket/70673
+    configure.perl  ${prefix}/bin/perl5
+}
 
 test.run            yes
 test.env            CC=${configure.cc}
diff --git a/devel/libtool/Portfile b/devel/libtool/Portfile
index 67674f49e4ad..302c002ea7ea 100644
--- a/devel/libtool/Portfile
+++ b/devel/libtool/Portfile
@@ -49,7 +49,7 @@ configure.env           M4=${prefix}/bin/gm4
 if {${os.platform} eq "darwin"} {
     configure.env-append    GREP=/usr/bin/grep SED=/usr/bin/sed
 } else {
-    depends_lib-append      port:grep port:gsed
+    depends_lib-append      port:grep port:gsed port:help2man
 }
 
 # Don't look for broken compilers (#23684, #32321).