diff --git a/.travis.yml b/.travis.yml
index bd3cd8b..bec01fd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,10 +1,11 @@
 language: c
 script: "./.travis-ci.sh"
 env:
-  - PACKAGE="piqi" OCAML_VERSION=3.12
-  - PACKAGE="piqi" OCAML_VERSION=4.00
-  - PACKAGE="piqi" OCAML_VERSION=4.01
-  - PACKAGE="piqi" OCAML_VERSION=4.02
-  - PACKAGE="piqi" OCAML_VERSION=4.03
-  # development version of piqilib
+  # NOTE: testing only against the current development version of piqilib,
+  # because compatibility is not guaranteed with previous releases
+  - PACKAGE="piqi" OCAML_VERSION=4.02 PINS=piqilib
   - PACKAGE="piqi" OCAML_VERSION=4.03 PINS=piqilib
+  - PACKAGE="piqi" OCAML_VERSION=4.04 PINS=piqilib
+  - PACKAGE="piqi" OCAML_VERSION=4.05 PINS=piqilib
+  - PACKAGE="piqi" OCAML_VERSION=4.06 PINS=piqilib
+  - PACKAGE="piqi" OCAML_VERSION=4.06 PINS=piqilib
diff --git a/opam b/opam
index 4f1a072..592c9b1 100644
--- a/opam
+++ b/opam
@@ -14,6 +14,7 @@ remove: [
   ["ocamlfind" "remove" "piqirun"]
 ]
 build-test: [make "test"]
+available: [ ocaml-version >= "4.02.0" ]
 depends: [
   "ocamlfind"
   "piqilib"
diff --git a/piqirun/Makefile b/piqirun/Makefile
index 75d1189..014803f 100644
--- a/piqirun/Makefile
+++ b/piqirun/Makefile
@@ -5,7 +5,7 @@ RESULT = piqirun
 
 
 # piqirun_ext.ml depends on it
-PACKS = piqilib bytes
+PACKS = piqilib
 
 
 SOURCES = \