diff --git a/crates/prune/types/src/mode.rs b/crates/prune/types/src/mode.rs
index d35cb66695..037e6fa496 100644
--- a/crates/prune/types/src/mode.rs
+++ b/crates/prune/types/src/mode.rs
@@ -40,7 +40,9 @@ impl PruneMode {
             }
             Self::Before(n) if *n == tip + 1 && purpose.is_static_file() => Some((tip, *self)),
             Self::Before(n) if *n > tip => None, // Nothing to prune yet
-            Self::Before(n) if tip - n >= segment.min_blocks(purpose) => Some((n - 1, *self)),
+            Self::Before(n) if tip - n >= segment.min_blocks(purpose) => {
+                Some(((*n).saturating_sub(1), *self))
+            }
             _ => return Err(PruneSegmentError::Configuration(segment)),
         };
         Ok(result)