diff --git a/ouroboros-consensus-cardano/changelog.d/20250212_120417_geo2a_issue_1340_add_proto_crypto_to_is_shelley_block.md b/ouroboros-consensus-cardano/changelog.d/20250212_120417_geo2a_issue_1340_add_proto_crypto_to_is_shelley_block.md
new file mode 100644
index 0000000000..22f995146a
--- /dev/null
+++ b/ouroboros-consensus-cardano/changelog.d/20250212_120417_geo2a_issue_1340_add_proto_crypto_to_is_shelley_block.md
@@ -0,0 +1,24 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+-->
+
+<!--
+### Patch
+
+- A bullet item for the Patch category.
+
+-->
+<!--
+### Non-Breaking
+
+- Add constraint an explicit on crypto to the `IsShelleyBlock` class
+
+-->
+<!--
+### Breaking
+
+- A bullet item for the Breaking category.
+
+-->
diff --git a/ouroboros-consensus-cardano/src/shelley/Ouroboros/Consensus/Shelley/Ledger/Block.hs b/ouroboros-consensus-cardano/src/shelley/Ouroboros/Consensus/Shelley/Ledger/Block.hs
index 8741301017..955fc408cb 100644
--- a/ouroboros-consensus-cardano/src/shelley/Ouroboros/Consensus/Shelley/Ledger/Block.hs
+++ b/ouroboros-consensus-cardano/src/shelley/Ouroboros/Consensus/Shelley/Ledger/Block.hs
@@ -139,6 +139,7 @@ mkShelleyBlock raw = ShelleyBlock {
 class
   ( ShelleyCompatible (BlockProtocol blk) (ShelleyBlockLedgerEra blk)
   , blk ~ ShelleyBlock (BlockProtocol blk) (ShelleyBlockLedgerEra blk)
+  , ProtoCrypto (BlockProtocol blk) ~ EraCrypto (ShelleyBlockLedgerEra blk)
   ) => IsShelleyBlock blk
 
 instance ( proto ~ BlockProtocol (ShelleyBlock proto era)