diff --git a/.github/workflows/manage-prs.yml b/.github/workflows/manage-prs.yml
index a38e9001..63442a05 100644
--- a/.github/workflows/manage-prs.yml
+++ b/.github/workflows/manage-prs.yml
@@ -49,8 +49,6 @@ jobs:
         run: |
           # See: https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-commands-for-github-actions#setting-an-environment-variable
           echo "MANAGER_PATH=${{ runner.temp }}/manager" >> "$GITHUB_ENV"
-          echo "INDEX_SOURCE_REPOSITORY_CHECKOUT_PATH=bcmi-labs/libraries-repository-engine" >> "$GITHUB_ENV"
-          echo "INDEX_SOURCE_PATH=repositories.txt" >> "$GITHUB_ENV" # Path of the LM index file under its repository.
 
       - name: Checkout local repository
         uses: actions/checkout@v2
@@ -77,18 +75,10 @@ jobs:
           git fetch origin pull/${{ github.event.pull_request.number }}${{ github.event.issue.number }}/head:pr-branch
           git checkout pr-branch
 
-      - name: Checkout index source list
-        uses: actions/checkout@v2
-        with:
-          repository: bcmi-labs/libraries-repository-engine
-          ref: production
-          token: ${{ secrets.REPO_SCOPE_TOKEN }}
-          path: ${{ env.INDEX_SOURCE_REPOSITORY_CHECKOUT_PATH }}
-
       - name: Parse request
         id: parse-request
         run: |
-          REQUEST="$("$MANAGER_PATH" --baseref="${{ github.sha }}" --repopath="${{ github.workspace }}" --listname="repositories.txt" --indexsourcepath="${{ env.INDEX_SOURCE_REPOSITORY_CHECKOUT_PATH }}/${{ env.INDEX_SOURCE_PATH }}")"
+          REQUEST="$("$MANAGER_PATH" --baseref="${{ github.sha }}" --repopath="${{ github.workspace }}" --listname="repositories.txt")"
           # Due to limitations of the GitHub Actions workflow system, dedicated outputs must be created for use in certain workflow fields.
           echo "::set-output name=type::$(echo "$REQUEST" | jq -r -c '.type')"
           echo "::set-output name=submissions::$(echo "$REQUEST" | jq -c '.submissions')"
diff --git a/manager/main.go b/manager/main.go
index 45852c31..bf67498e 100644
--- a/manager/main.go
+++ b/manager/main.go
@@ -78,7 +78,6 @@ type submissionType struct {
 var baseRef = flag.String("baseref", "", "")
 var repoPath = flag.String("repopath", "", "")
 var listName = flag.String("listname", "", "")
-var indexSourcePath = flag.String("indexsourcepath", "", "")
 
 func main() {
 	// Validate flag input.
@@ -105,19 +104,6 @@ func main() {
 		errorExit(fmt.Sprintf("list file %s not found", listPath))
 	}
 
-	if *indexSourcePath == "" {
-		errorExit("--indexsourcepath flag is required")
-	}
-
-	indexSourcePath := paths.New(*indexSourcePath)
-	exist, err = indexSourcePath.ExistCheck()
-	if err != nil {
-		panic(err)
-	}
-	if !exist {
-		errorExit(fmt.Sprintf("index source file %s not found", indexSourcePath))
-	}
-
 	// Get the PR diff.
 	err = os.Chdir(*repoPath)
 	if err != nil {
@@ -137,7 +123,7 @@ func main() {
 	// Process the submissions.
 	var indexEntries []string
 	for _, submissionURL := range submissionURLs {
-		submission, indexEntry := populateSubmission(submissionURL, indexSourcePath)
+		submission, indexEntry := populateSubmission(submissionURL, listPath)
 		request.Submissions = append(request.Submissions, submission)
 		indexEntries = append(indexEntries, indexEntry)
 	}
@@ -216,7 +202,7 @@ func parseDiff(rawDiff []byte, listName string) (string, []string) {
 }
 
 // populateSubmission does the checks on the submission that aren't provided by Arduino Lint and gathers the necessary data on it.
-func populateSubmission(submissionURL string, indexSourcePath *paths.Path) (submissionType, string) {
+func populateSubmission(submissionURL string, listPath *paths.Path) (submissionType, string) {
 	indexSourceSeparator := "|"
 	var submission submissionType
 
@@ -256,11 +242,24 @@ func populateSubmission(submissionURL string, indexSourcePath *paths.Path) (subm
 	}
 
 	// Check if the URL is already in the index.
-	indexSourceLines, err := indexSourcePath.ReadFileAsLines()
-	for _, indexSourceLine := range indexSourceLines {
-		if strings.HasPrefix(indexSourceLine, fmt.Sprintf("%s%s", normalizedURLObject.String(), indexSourceSeparator)) {
-			submission.Error = "Submission URL is already in the Library Manager index."
-			return submission, ""
+	listLines, err := listPath.ReadFileAsLines()
+	occurrences := 0
+	for _, listURL := range listLines {
+		listURLObject, err := url.Parse(strings.TrimSpace(listURL))
+		if err != nil {
+			panic(err) // All list items have already passed parsing so something is broken if this happens.
+		}
+		normalizedListURLObject, err := normalizeURL(listURLObject)
+		if err != nil {
+			panic(fmt.Errorf("When processing list item %s: %s", listURL, err)) // All list items have already been through normalization without error so something is broken if this happens.
+		}
+
+		if normalizedListURLObject.String() == normalizedURLObject.String() {
+			occurrences++
+			if occurrences > 1 {
+				submission.Error = "Submission URL is already in the Library Manager index."
+				return submission, ""
+			}
 		}
 	}