diff --git a/NEWS b/NEWS
index 4fbad22..edc8702 100644
--- a/NEWS
+++ b/NEWS
@@ -152,3 +152,7 @@ v1.5.5:
 * bz3_decompress (API) and the CLI: reject block headers with negative sizes or original sizes exceeding the block size.
 * lzp/rle decoders: fix integer overflows in match and run length accumulation on malformed input (#191, #192).
 * ci: weekly scheduled builds, dependabot for GitHub Actions, fix clang builds on armv6.
+
+v1.5.6:
+* bz3_bound (API): increase the constant slack from 32 to 50 bytes. Previously, `bz3_compress` could write up
+  to 4 bytes past an output buffer of exactly `bz3_bound(in_size)` bytes for small, incompressible inputs.
diff --git a/src/libbz3.c b/src/libbz3.c
index e5a7896..501e2c9 100644
--- a/src/libbz3.c
+++ b/src/libbz3.c
@@ -514,7 +514,7 @@ BZIP3_API s8 bz3_last_error(struct bz3_state * state) { return state->last_error
 
 BZIP3_API const char * bz3_version(void) { return VERSION; }
 
-BZIP3_API size_t bz3_bound(size_t input_size) { return input_size + input_size / 50 + 32; }
+BZIP3_API size_t bz3_bound(size_t input_size) { return input_size + input_size / 50 + 50; }
 
 BZIP3_API const char * bz3_strerror(struct bz3_state * state) {
     switch (state->last_error) {