diff --git a/poky/meta/classes/externalsrc.bbclass b/poky/meta/classes/externalsrc.bbclass
index aedd78a..cba80bb 100644
--- a/poky/meta/classes/externalsrc.bbclass
+++ b/poky/meta/classes/externalsrc.bbclass
@@ -63,6 +63,7 @@
         else:
             d.setVar('B', '${WORKDIR}/${BPN}-${PV}')
 
+        bb.fetch.get_hashvalue(d)
         local_srcuri = []
         fetch = bb.fetch2.Fetch((d.getVar('SRC_URI') or '').split(), d)
         for url in fetch.urls:
@@ -73,8 +74,6 @@
 
         d.setVar('SRC_URI', ' '.join(local_srcuri))
 
-        # Dummy value because the default function can't be called with blank SRC_URI
-        d.setVar('SRCPV', '999')
         # sstate is never going to work for external source trees, disable it
         d.setVar('SSTATE_SKIP_CREATION', '1')
 
@@ -126,6 +125,9 @@
         d.setVarFlag('do_compile', 'file-checksums', '${@srctree_hash_files(d)}')
         d.setVarFlag('do_configure', 'file-checksums', '${@srctree_configure_hash_files(d)}')
 
+        d.appendVarFlag('do_compile', 'prefuncs', ' fetcher_hashes_dummyfunc')
+        d.appendVarFlag('do_configure', 'prefuncs', ' fetcher_hashes_dummyfunc')
+
         # We don't want the workdir to go away
         d.appendVar('RM_WORK_EXCLUDE', ' ' + d.getVar('PN'))