diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4daeeaa..30efe46 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -18,6 +18,7 @@ jobs:
               #- windows-latest
         ocaml-compiler:
             - '4.08.x'
+            - '4.12.x'
             - '4.14.x'
             - '5.0.x'
 
@@ -31,9 +32,13 @@ jobs:
           dune-cache: true
           allow-prerelease-opam: true
 
-      - run: opam install -t trace trace-tef --deps-only
-      - run: opam exec -- dune build '@install' -p trace,trace-tef
+      - run: opam install -t trace trace-tef trace-fuchsia --deps-only
+      - run: opam install ppx_trace --deps-only # no tests
+        if: matrix.ocaml-compiler != '4.08.x'
+      - run: opam exec -- dune build '@install' -p trace,trace-tef,trace-fuchsia
+      - run: opam exec -- dune build '@install' -p ppx_trace
+        if: matrix.ocaml-compiler != '4.08.x'
       - run: opam exec -- dune runtest -p trace
       - run: opam install trace
-      - run: opam exec -- dune runtest -p trace-tef
+      - run: opam exec -- dune runtest -p trace-tef,trace-fuchsia
 
diff --git a/dune-project b/dune-project
index 7ef9017..5fa9740 100644
--- a/dune-project
+++ b/dune-project
@@ -33,7 +33,7 @@
    (trace-tef (and (= :version) :with-test))
    dune)
  (tags
-  (trace tracing observability profiling ppx)))
+  (trace ppx)))
 
 (package
  (name trace-tef)
@@ -45,7 +45,7 @@
    base-unix
    dune)
  (tags
-  (trace tracing catapult)))
+  (trace tracing catapult TEF chrome-format)))
 
 (package
  (name trace-fuchsia)
diff --git a/ppx_trace.opam b/ppx_trace.opam
index 818df8b..74281a9 100644
--- a/ppx_trace.opam
+++ b/ppx_trace.opam
@@ -5,7 +5,7 @@ synopsis: "ppx-based instrumentation for trace"
 maintainer: ["Simon Cruanes"]
 authors: ["Simon Cruanes"]
 license: "MIT"
-tags: ["trace" "tracing" "observability" "profiling" "ppx"]
+tags: ["trace" "ppx"]
 homepage: "https://github.com/c-cube/ocaml-trace"
 bug-reports: "https://github.com/c-cube/ocaml-trace/issues"
 depends: [
diff --git a/src/fuchsia/write/buf.ml b/src/fuchsia/write/buf.ml
index 52ac55a..b2aae8a 100644
--- a/src/fuchsia/write/buf.ml
+++ b/src/fuchsia/write/buf.ml
@@ -29,8 +29,7 @@ let[@inline] add_string (self : t) (s : string) : unit =
   let missing = missing_to_round len in
 
   (* bound check *)
-  assert (len + missing + self.offset <= Bytes.length self.buf);
-  Bytes.unsafe_blit_string s 0 self.buf self.offset len;
+  Bytes.blit_string s 0 self.buf self.offset len;
   self.offset <- self.offset + len;
 
   (* add 0-padding *)
diff --git a/trace-tef.opam b/trace-tef.opam
index d984efa..9b29e6f 100644
--- a/trace-tef.opam
+++ b/trace-tef.opam
@@ -6,7 +6,7 @@ synopsis:
 maintainer: ["Simon Cruanes"]
 authors: ["Simon Cruanes"]
 license: "MIT"
-tags: ["trace" "tracing" "catapult"]
+tags: ["trace" "tracing" "catapult" "TEF" "chrome-format"]
 homepage: "https://github.com/c-cube/ocaml-trace"
 bug-reports: "https://github.com/c-cube/ocaml-trace/issues"
 depends: [