diff --git a/src/crypto/mishmash/cmd_md4.c b/src/crypto/mishmash/cmd_md4.c
index 8991b0250..390a533db 100644
--- a/src/crypto/mishmash/cmd_md4.c
+++ b/src/crypto/mishmash/cmd_md4.c
@@ -22,6 +22,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( FORBIDDEN );
 
 #include <ipxe/md4.h>
 #include <hci/digest_cmd.h>
diff --git a/src/crypto/mishmash/oid_md4.c b/src/crypto/mishmash/oid_md4.c
index d42f2df19..03b893d47 100644
--- a/src/crypto/mishmash/oid_md4.c
+++ b/src/crypto/mishmash/oid_md4.c
@@ -22,6 +22,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( FORBIDDEN );
 
 #include <ipxe/md4.h>
 #include <ipxe/asn1.h>
diff --git a/src/crypto/mishmash/oid_md5.c b/src/crypto/mishmash/oid_md5.c
index f56dd8b8d..0095fbe0e 100644
--- a/src/crypto/mishmash/oid_md5.c
+++ b/src/crypto/mishmash/oid_md5.c
@@ -22,6 +22,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( FORBIDDEN );
 
 #include <ipxe/md5.h>
 #include <ipxe/asn1.h>
diff --git a/src/crypto/mishmash/rsa_md5.c b/src/crypto/mishmash/rsa_md5.c
index 051afe264..00808c23f 100644
--- a/src/crypto/mishmash/rsa_md5.c
+++ b/src/crypto/mishmash/rsa_md5.c
@@ -22,6 +22,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( FORBIDDEN );
 
 #include <ipxe/rsa.h>
 #include <ipxe/md5.h>