diff --git a/parsec-fix-old-rust.patch b/parsec-fix-old-rust.patch
new file mode 100644
index 0000000..46b9265
--- /dev/null
+++ b/parsec-fix-old-rust.patch
@@ -0,0 +1,53 @@
+From f9688c44319c1733586d6fbc3b3c24a403deaed8 Mon Sep 17 00:00:00 2001
+From: Hugues de Valon <hugues.devalon@arm.com>
+Date: Fri, 30 Apr 2021 10:48:37 +0100
+Subject: [PATCH] Make it compile for Rust 1.43.1
+
+The From trait was not implemented for that version of Rust. Uses the
+to_vec method which achieves the same thing.
+
+Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
+---
+ src/providers/pkcs11/key_management.rs | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/src/providers/pkcs11/key_management.rs b/src/providers/pkcs11/key_management.rs
+index 6bc5e06..73ce607 100644
+--- a/src/providers/pkcs11/key_management.rs
++++ b/src/providers/pkcs11/key_management.rs
+@@ -27,7 +27,7 @@ impl Provider {
+         key_id: u32,
+         key_type: KeyPairType,
+     ) -> Result<ObjectHandle> {
+-        let mut template = vec![Attribute::Id(key_id.to_be_bytes().into())];
++        let mut template = vec![Attribute::Id(key_id.to_be_bytes().to_vec())];
+ 
+         match key_type {
+             KeyPairType::PublicKey => template.push(Attribute::Class(ObjectClass::PUBLIC_KEY)),
+@@ -103,7 +103,7 @@ impl Provider {
+         let key_id = self.create_key_id();
+ 
+         let mut pub_template = vec![
+-            Attribute::Id(key_id.to_be_bytes().into()),
++            Attribute::Id(key_id.to_be_bytes().to_vec()),
+             Attribute::Token(true.into()),
+             Attribute::AllowedMechanisms(vec![Mechanism::try_from(
+                 key_attributes.policy.permitted_algorithms,
+@@ -122,7 +122,7 @@ impl Provider {
+         let mech = match key_attributes.key_type {
+             Type::RsaKeyPair => {
+                 pub_template.push(Attribute::Private(false.into()));
+-                pub_template.push(Attribute::PublicExponent(utils::PUBLIC_EXPONENT.into()));
++                pub_template.push(Attribute::PublicExponent(utils::PUBLIC_EXPONENT.to_vec()));
+                 pub_template.push(Attribute::ModulusBits(
+                     key_attributes.bits.try_into().map_err(to_response_status)?,
+                 ));
+@@ -225,7 +225,7 @@ impl Provider {
+         template.push(Attribute::PublicExponent(exponent_object.into()));
+         template.push(Attribute::Verify(true.into()));
+         template.push(Attribute::Encrypt(true.into()));
+-        template.push(Attribute::Id(key_id.to_be_bytes().into()));
++        template.push(Attribute::Id(key_id.to_be_bytes().to_vec()));
+         template.push(Attribute::Private(false.into()));
+         template.push(Attribute::AllowedMechanisms(vec![MechanismType::RSA_PKCS]));
+ 
diff --git a/parsec.changes b/parsec.changes
index 72a7ecf..831196a 100644
--- a/parsec.changes
+++ b/parsec.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Fri Apr 30 11:36:56 UTC 2021 - Guillaume GARDET <guillaume.gardet@opensuse.org>
+
+- Fix build with old rust used in Leap 15.3/SLE15-SP3.
+  * parsec-fix-old-rust.patch
+
 -------------------------------------------------------------------
 Wed Apr 14 14:54:32 UTC 2021 - Guillaume GARDET <guillaume.gardet@opensuse.org>
 
diff --git a/parsec.spec b/parsec.spec
index a0b4cb3..4932685 100644
--- a/parsec.spec
+++ b/parsec.spec
@@ -35,6 +35,8 @@ Source3:        parsec.service
 Source4:        config.toml
 Source5:        parsec.conf
 Source6:        system-user-parsec.conf
+# Fix build with old rust used in Leap 15.3/SLE15-SP3 - https://github.com/parallaxsecond/parsec/issues/409
+Patch1:         parsec-fix-old-rust.patch
 BuildRequires:  cargo
 BuildRequires:  clang-devel
 BuildRequires:  cmake