diff --git a/Cargo.toml b/Cargo.toml
index 99cca63..7c98c7c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,7 @@ members = ["crates/*"]
 resolver = "2"
 
 [workspace.package]
-version = "0.16.0-rc.3"
+version = "0.16.0-rc.4"
 edition = "2024"
 rust-version = "1.88"
 authors = ["init4"]
diff --git a/crates/block-processor/src/v1/processor.rs b/crates/block-processor/src/v1/processor.rs
index 9897a87..04be3c4 100644
--- a/crates/block-processor/src/v1/processor.rs
+++ b/crates/block-processor/src/v1/processor.rs
@@ -248,10 +248,13 @@ where
             .wrap_err("parent ru block not present in DB")
             .inspect_err(|e| error!(%e))?;
 
-        let slot = self.slot_calculator.slot_ending_at(timestamp).expect("host chain has started");
-
         let txns = match &block_extracts.submitted {
             Some(submitted) => {
+                // NB: Pre-merge blocks do not have predictable slot times.
+                let slot = self
+                    .slot_calculator
+                    .slot_ending_at(timestamp)
+                    .expect("expect submitted events only occur post-merge");
                 self.blob_cacher
                     .signet_block(block_extracts.host_block.number(), slot, submitted)
                     .await?