diff --git a/src/lib/convert-issue-to-spdx.ts b/src/lib/convert-issue-to-spdx.ts
index d751a93..32c36e1 100644
--- a/src/lib/convert-issue-to-spdx.ts
+++ b/src/lib/convert-issue-to-spdx.ts
@@ -12,13 +12,17 @@ function getVulnerabilityRating(
   const vulnerabilityRating: types.VulnerabilityRating = {
     method: issue.CVSSv3 ? 'CVSS_3' : undefined, // must be CVSS_2, CVSS_3, OWASP_RISK or OTHER
     score: [vulnerabilityRatingScore],
-    severity: issue.severity, // exploitability score of the vulnerability either None, Low, Medium, High or Critical
+    severity: capitalize(issue.severity), // exploitability score of the vulnerability either None, Low, Medium, High or Critical
     vector: issue.CVSSv3,
   };
 
   return [vulnerabilityRating];
 }
 
+function capitalize(str: string) {
+  return str[0].toUpperCase() + str.slice(1);
+}
+
 function getExternalReferencesRelationships(
   references: types.SnykIssueReference[],
 ): types.ExternalReferencesRelationship[] {
diff --git a/test/unit/lib/__snapshots__/convert-issue-to-spdx.spec.ts.snap b/test/unit/lib/__snapshots__/convert-issue-to-spdx.spec.ts.snap
index ebc8653..fb8d294 100644
--- a/test/unit/lib/__snapshots__/convert-issue-to-spdx.spec.ts.snap
+++ b/test/unit/lib/__snapshots__/convert-issue-to-spdx.spec.ts.snap
@@ -108,7 +108,7 @@ Upgrade \`json\` to version 2.3.0 or higher.
                 "impact": "<2.3.0",
               },
             ],
-            "severity": "high",
+            "severity": "High",
             "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H",
           },
         ],