diff --git a/src/libsaml.ts b/src/libsaml.ts
index 4159cbd2..18e5eba7 100644
--- a/src/libsaml.ts
+++ b/src/libsaml.ts
@@ -357,6 +357,9 @@ const libSaml = () => {
           const certificateNode = select(".//*[local-name(.)='X509Certificate']", signatureNode) as any;
           // certificate in metadata
           let metadataCert: any = opts.metadata.getX509Certificate(certUse.signing);
+          if (!metadataCert) {
+            throw new Error('INVALID_CERTIFICATE_PROVIDED')
+          }
           // flattens the nested array of Certificates from each KeyDescriptor
           if (Array.isArray(metadataCert)) {
             metadataCert = flattenDeep(metadataCert);