diff --git a/Userland/Libraries/LibCrypto/PK/Code/EMSA_PSS.h b/Userland/Libraries/LibCrypto/PK/Code/EMSA_PSS.h
index 4e2b10c498..b1b1a569a9 100644
--- a/Userland/Libraries/LibCrypto/PK/Code/EMSA_PSS.h
+++ b/Userland/Libraries/LibCrypto/PK/Code/EMSA_PSS.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <AK/Array.h>
+#include <AK/Format.h>
 #include <AK/Random.h>
 #include <LibCrypto/PK/Code/Code.h>