diff --git a/src/issue-enhancers/category-merge-to-tags-enhancer.ts b/src/issue-enhancers/category-merge-to-tags-enhancer.ts
index f6ef88d..989975e 100644
--- a/src/issue-enhancers/category-merge-to-tags-enhancer.ts
+++ b/src/issue-enhancers/category-merge-to-tags-enhancer.ts
@@ -15,14 +15,14 @@ export class CategoryMergeToTagsEnhancer implements IssueEnhancerInterface {
   async enhance(
     issue: RedmineTypes.ExtendedIssue,
   ): Promise<RedmineTypes.ExtendedIssue> {
-    if (this.forProjects.indexOf(issue.project.name) < 0) {
+    if (!issue || !issue?.project?.name || this.forProjects.indexOf(issue.project.name) < 0) {
       return issue;
     }
     if (!issue.tags || !this.isArray(issue.tags)) {
       issue.tags = [];
     }
-    const category = issue.category.name.toLowerCase().replaceAll(' ', '');
-    if (issue.tags.indexOf(category) < 0) {
+    const category = issue?.category?.name?.toLowerCase()?.replaceAll(' ', '_');
+    if (category && issue.tags.indexOf(category) < 0) {
       issue.tags.push(category);
     }
     return issue;