diff --git a/bin/mergedevbranch b/bin/mergedevbranch
index 0f94242f9..d005850dd 100755
--- a/bin/mergedevbranch
+++ b/bin/mergedevbranch
@@ -113,6 +113,10 @@ cwd=${PWD##*/}
 branch=$1
 rev=$2
 fix=$3
+
+# remove leading 'r' from rev, if present
+rev=${rev#r}
+
 repo=$(echo -n "$(svn info | grep "^Repository Root: " | sed 's/Repository Root: //')")
 
 note "Identify the branch:"
@@ -128,6 +132,9 @@ else
     die "Could not find a branch matching '$branch'"
 fi
 
+note "Svn update, to make sure we don't have a mixed revision working copy"
+svn update -q
+
 mergelog=$(mktemp)
 svn propget svn:mergeinfo . > $mergelog