diff --git a/cmd_gen/main.go b/cmd_gen/main.go
index 1c4e38a..81b0288 100644
--- a/cmd_gen/main.go
+++ b/cmd_gen/main.go
@@ -33,6 +33,7 @@ var (
 	// Commandline flags: should be string if it may not exist
 	modelRoot          string // modelRoot is the root directory of the models.
 	repoSlug           string // repoSlug is the "owner/repo" name of the models repo (e.g. openconfig/public).
+	prHeadRepoURL      string // prHeadRepoURL is the URL of the HEAD repo for PRs (e.g. https://github.com/openconfig/public).
 	commitSHA          string
 	branchName         string // branchName is the name of the branch where the commit occurred.
 	prNumberStr        string // prNumberStr is the PR number.
@@ -41,9 +42,11 @@ var (
 	skippedValidators  string // e.g. "yanglint,pyang@head"
 
 	// Derived flags (for ease of use)
-	owner    string
-	repo     string
-	prNumber int
+	owner     string
+	repo      string
+	prNumber  int
+	headOwner string
+	headRepo  string
 
 	// local run flags
 	local             bool   // local run toggle
@@ -68,7 +71,8 @@ var (
 func init() {
 	// GCB-required flags
 	flag.StringVar(&modelRoot, "modelRoot", "", "root directory to OpenConfig models")
-	flag.StringVar(&repoSlug, "repo-slug", "openconfig/public", "repo where CI is run")
+	flag.StringVar(&repoSlug, "repo-slug", "", "repo where CI is run")
+	flag.StringVar(&prHeadRepoURL, "pr-head-repo-url", "", "PR head repo URL")
 	flag.StringVar(&commitSHA, "commit-sha", "", "commit SHA of the PR")
 	flag.StringVar(&prNumberStr, "pr-number", "", "PR number")
 	flag.StringVar(&branchName, "branch", "", "branch name of commit")
@@ -266,6 +270,7 @@ func postInitialStatus(g *commonci.GithubRequestHandler, validatorId string, ver
 
 	if err := g.UpdatePRStatus(update); err != nil {
 		log.Printf("error: couldn't update PR: %s", err)
+		log.Printf("GithubPRUpdate: %+v", update)
 		return err
 	}
 	return nil
@@ -333,6 +338,13 @@ func main() {
 		}
 	}
 
+	if err := os.MkdirAll(commonci.ResultsDir, 0644); err != nil {
+		log.Fatalf("error while creating directory %q: %v", commonci.ResultsDir, err)
+	}
+	if err := os.MkdirAll(commonci.UserConfigDir, 0644); err != nil {
+		log.Fatalf("error while creating directory %q: %v", commonci.UserConfigDir, err)
+	}
+
 	repoSplit := strings.Split(repoSlug, "/")
 	owner = repoSplit[0]
 	repo = repoSplit[1]
@@ -340,16 +352,21 @@ func main() {
 		log.Fatalf("no commit SHA")
 	}
 
-	h, err := commonci.NewGitHubRequestHandler()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	if err := os.MkdirAll(commonci.ResultsDir, 0644); err != nil {
-		log.Fatalf("error while creating directory %q: %v", commonci.ResultsDir, err)
-	}
-	if err := os.MkdirAll(commonci.UserConfigDir, 0644); err != nil {
-		log.Fatalf("error while creating directory %q: %v", commonci.UserConfigDir, err)
+	headOwner = owner
+	headRepo = repo
+	if prHeadRepoURL != "" {
+		// Expected format: e.g. https://github.com/openconfig/public
+		URLSplit := strings.Split(prHeadRepoURL, "/")
+		headOwner = URLSplit[len(URLSplit)-2]
+		headRepo = URLSplit[len(URLSplit)-1]
+		if headOwner != owner || headRepo != repo {
+			remoteBranch := headOwner + "/" + headRepo
+			// If this is a fork, let later CI steps know the fork repo slug.
+			if err := ioutil.WriteFile(commonci.ForkSlugFile, []byte(remoteBranch), 0444); err != nil {
+				log.Fatalf("error while writing fork slug file %q: %v", commonci.ForkSlugFile, err)
+			}
+			log.Printf("fork detected for remote repo %q", remoteBranch)
+		}
 	}
 
 	compatReports = commonci.ValidatorAndVersionsDiff(compatReports, skippedValidators)
@@ -364,6 +381,10 @@ func main() {
 	_, skippedValidatorsMap := commonci.GetValidatorAndVersionsFromString(skippedValidators)
 
 	// Generate validation scripts, files, and post initial status on GitHub.
+	h, err := commonci.NewGitHubRequestHandler()
+	if err != nil {
+		log.Fatal(err)
+	}
 	for validatorId, validator := range commonci.Validators {
 		if validator.ReportOnly {
 			continue
diff --git a/commonci/commonci.go b/commonci/commonci.go
index dc12dfc..db5370f 100644
--- a/commonci/commonci.go
+++ b/commonci/commonci.go
@@ -39,6 +39,9 @@ const (
 	// CompatReportValidatorsFile notifies later CI steps of the validators
 	// that should be reported as a compatibility report.
 	CompatReportValidatorsFile = UserConfigDir + "/compat-report-validators.txt"
+	// ForkSlugFile is created by cmd_gen to store the fork slug, if
+	// present, for later CI steps.
+	ForkSlugFile = UserConfigDir + "/fork-slug.txt"
 	// ScriptFileName by convention is the script with the validator commands.
 	ScriptFileName = "script.sh"
 	// LatestVersionFileName by convention contains the version description
diff --git a/validators/confd/test.sh b/validators/confd/test.sh
index b4b1864..5e0e49d 100755
--- a/validators/confd/test.sh
+++ b/validators/confd/test.sh
@@ -15,7 +15,7 @@ unzip $ZIP_FILE -d $RESULTSDIR/confd-unzipped
 find $RESULTSDIR/confd-unzipped -name 'confd-basic-*.linux.x86_64.installer.bin' -exec {} $RESULTSDIR/confd-install \;
 CONFDC=$RESULTSDIR/confd-install/bin/confdc
 
-CONFDPATH=`find $_MODEL_ROOT -type d | tr '\n' ':'`:$_MODEL_ROOT/../third_party/ietf
+CONFDPATH=`find $_MODEL_ROOT -type d | tr '\n' ':'`:$ROOT_DIR/third_party/ietf
 
 $CONFDC --version > $RESULTSDIR/latest-version.txt
 if bash $RESULTSDIR/script.sh $CONFDC $CONFDPATH > $OUTFILE 2> $FAILFILE; then
diff --git a/validators/misc-checks/test.sh b/validators/misc-checks/test.sh
index b2a9111..97046c9 100755
--- a/validators/misc-checks/test.sh
+++ b/validators/misc-checks/test.sh
@@ -24,7 +24,7 @@ find $_MODEL_ROOT -name '*.yang' > $RESULTSDIR/all-non-empty-files.txt 2>> $OUTF
 # This requires the check logic within post_results to be changed.
 # I'm delaying this because it remains to be seen whether goyang can be
 # refactored so we don't need do this inter-process communication via files.
-if bash $RESULTSDIR/script.sh > $OUTFILE 2>> $FAILFILE; then
+if bash $RESULTSDIR/script.sh >> $OUTFILE 2>> $FAILFILE; then
   # Delete fail file if it's empty and the script passed.
   find $FAILFILE -size 0 -delete
 fi
@@ -32,13 +32,17 @@ cat $RESULTSDIR/*.pr-file-parse-log > $RESULTSDIR/pr-file-parse-log 2>> $OUTFILE
 
 # changed-files.txt
 REPODIR=$RESULTSDIR/base_repo
-git clone -b $BRANCH_NAME "git@github.com:$_REPO_SLUG.git" $REPODIR
+git clone "git@github.com:$_REPO_SLUG.git" $REPODIR
 cd $REPODIR
-BASE_COMMIT=$(git merge-base $COMMIT_SHA origin/master)
+PRBRANCH=gcb-ci-remote-repo-long-name-to-avoid-conflict
+# fetching the PR directly from GitHub handles both normal PRs as well as forks.
+git fetch origin pull/$_PR_NUMBER/head:$PRBRANCH
+git checkout $PRBRANCH
+BASE_COMMIT=$(git merge-base $PRBRANCH origin/master)
 git diff --name-only $BASE_COMMIT | grep -E '.*\.yang$' > $RESULTSDIR/changed-files.txt 2>> $OUTFILE
 
 # master-file-parse-log
-git checkout $BASE_COMMIT &> $OUTFILE
+git checkout $BASE_COMMIT &>> $OUTFILE
 if find $REPODIR -name '*.yang' | xargs $GOPATH/bin/ocversion -p $REPODIR > $RESULTSDIR/master-file-parse-log 2>> $FAILFILE; then
   # Delete fail file if it's empty and the script passed.
   find $FAILFILE -size 0 -delete