diff --git a/CODE_SIGNING.md b/CODE_SIGNING.md
index fde3cae7..b701888d 100644
--- a/CODE_SIGNING.md
+++ b/CODE_SIGNING.md
@@ -146,4 +146,5 @@ $
 ## Sources
 
 * [Private Key Generation and CSR Attestation with YubiKey Manager
-](https://signmycode.com/resources/private-key-generation-and-csr-attestation-with-yubikey-manager) - SignMyCode.com
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+](https://signmycode.com/resources/private-key-generation-and-csr-attestation-with-yubikey-manager) - SignMyCode.com
+* [Yubico GitHub issue referring to osslsigncode](https://github.com/Yubico/yubico-piv-tool/issues/21)
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