diff --git a/polkadot/node/malus/src/variants/common.rs b/polkadot/node/malus/src/variants/common.rs
index 92264cd653d0..011fcc80e373 100644
--- a/polkadot/node/malus/src/variants/common.rs
+++ b/polkadot/node/malus/src/variants/common.rs
@@ -188,7 +188,7 @@ where
 		let _candidate_descriptor = candidate_descriptor.clone();
 		let mut subsystem_sender = subsystem_sender.clone();
 		let (sender, receiver) = std::sync::mpsc::channel();
-		self.spawner.spawn(
+		self.spawner.spawn_blocking(
 			"malus-get-validation-data",
 			Some("malus"),
 			Box::pin(async move {
diff --git a/polkadot/node/malus/src/variants/dispute_finalized_candidates.rs b/polkadot/node/malus/src/variants/dispute_finalized_candidates.rs
index 113ab026879d..7f83c386090e 100644
--- a/polkadot/node/malus/src/variants/dispute_finalized_candidates.rs
+++ b/polkadot/node/malus/src/variants/dispute_finalized_candidates.rs
@@ -95,7 +95,7 @@ where
 
 				let dispute_offset = self.dispute_offset;
 				let mut sender = subsystem_sender.clone();
-				self.spawner.spawn(
+				self.spawner.spawn_blocking(
 					"malus-dispute-finalized-block",
 					Some("malus"),
 					Box::pin(async move {
diff --git a/polkadot/node/malus/src/variants/suggest_garbage_candidate.rs b/polkadot/node/malus/src/variants/suggest_garbage_candidate.rs
index 817afb58437e..cf0ff5f809d8 100644
--- a/polkadot/node/malus/src/variants/suggest_garbage_candidate.rs
+++ b/polkadot/node/malus/src/variants/suggest_garbage_candidate.rs
@@ -113,7 +113,7 @@ where
 					let (sender, receiver) = std::sync::mpsc::channel();
 					let mut new_sender = subsystem_sender.clone();
 					let _candidate = candidate.clone();
-					self.spawner.spawn(
+					self.spawner.spawn_blocking(
 						"malus-get-validation-data",
 						Some("malus"),
 						Box::pin(async move {
diff --git a/prdoc/pr_2804.prdoc b/prdoc/pr_2804.prdoc
new file mode 100644
index 000000000000..456120741d93
--- /dev/null
+++ b/prdoc/pr_2804.prdoc
@@ -0,0 +1,9 @@
+title: Fix malus implementation.
+
+doc:
+  - audience: Node Dev
+    description: |
+      The malus implementation is used to test security of Polkadot.
+      It was broken. This fixes it.
+
+crates: [ ]