1 files changed, 1 insertions, 0 deletions
diff --git a/src/platform.rs b/src/platform.rs
index 3f47718..590a77c 100644
--- a/src/platform.rs
+++ b/src/platform.rs
@@ -286,6 +286,7 @@ impl Platform {
         flags: u8,
         out: &mut [u8],
     ) {
+        debug_assert_eq!(0, out.len() % BLOCK_LEN, "whole blocks only");
         if out.is_empty() {
             // The current assembly implementation always outputs at least 1 block.
             return;