diff --git a/pkgs/development/ocaml-modules/biniou/default.nix b/pkgs/development/ocaml-modules/biniou/default.nix
index 59f30de5e841..565176276f98 100644
--- a/pkgs/development/ocaml-modules/biniou/default.nix
+++ b/pkgs/development/ocaml-modules/biniou/default.nix
@@ -4,6 +4,9 @@ let
   version = "1.0.9";
   webpage = "http://mjambon.com/${pname}.html";
 in
+
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.11";
+
 stdenv.mkDerivation rec {
 
   name = "${pname}-${version}";
@@ -23,10 +26,11 @@ stdenv.mkDerivation rec {
     mkdir $out/bin
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "A binary data format designed for speed, safety, ease of use and backward compatibility as protocols evolve";
     homepage = "${webpage}";
-    license = stdenv.lib.licenses.bsd3;
+    license = licenses.bsd3;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
diff --git a/pkgs/development/ocaml-modules/cmdliner/default.nix b/pkgs/development/ocaml-modules/cmdliner/default.nix
index 3a00f0c3888c..2dfd7ba12860 100644
--- a/pkgs/development/ocaml-modules/cmdliner/default.nix
+++ b/pkgs/development/ocaml-modules/cmdliner/default.nix
@@ -5,6 +5,9 @@ let
   version = "0.9.5";
   ocaml_version = (builtins.parseDrvName ocaml.name).version;
 in
+
+assert stdenv.lib.versionAtLeast ocaml_version "3.12";
+
 stdenv.mkDerivation {
 
   name = "ocaml-${pname}-${version}";
@@ -31,6 +34,7 @@ stdenv.mkDerivation {
     homepage = http://erratique.ch/software/cmdliner;
     description = "An OCaml module for the declarative definition of command line interfaces";
     license = licenses.bsd3;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
diff --git a/pkgs/development/ocaml-modules/csv/default.nix b/pkgs/development/ocaml-modules/csv/default.nix
index 7178452e3dda..09679ced7444 100644
--- a/pkgs/development/ocaml-modules/csv/default.nix
+++ b/pkgs/development/ocaml-modules/csv/default.nix
@@ -1,4 +1,7 @@
 {stdenv, fetchurl, ocaml, findlib}:
+
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.11";
+
 stdenv.mkDerivation {
 
   name = "ocaml-csv-1.3.3";
@@ -18,10 +21,11 @@ stdenv.mkDerivation {
 
   installPhase = "ocaml setup.ml -install";
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "A pure OCaml library to read and write CSV files";
     homepage = "https://forge.ocamlcore.org/projects/csv/";
-    license = stdenv.lib.licenses.lgpl21;
+    license = licenses.lgpl21;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
diff --git a/pkgs/development/ocaml-modules/easy-format/default.nix b/pkgs/development/ocaml-modules/easy-format/default.nix
index d01a4edf26ec..0554b67f1d78 100644
--- a/pkgs/development/ocaml-modules/easy-format/default.nix
+++ b/pkgs/development/ocaml-modules/easy-format/default.nix
@@ -17,11 +17,10 @@ stdenv.mkDerivation rec {
 
   createFindlibDestdir = true;
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "A high-level and functional interface to the Format module of the OCaml standard library";
     homepage = "${webpage}";
-    license = "bsd";
+    license = licenses.bsd3;
+    maintainers = [ maintainers.vbgl ];
   };
 }
-
-
diff --git a/pkgs/development/ocaml-modules/extlib/default.nix b/pkgs/development/ocaml-modules/extlib/default.nix
index 7bc7e3989488..45a859c146f3 100644
--- a/pkgs/development/ocaml-modules/extlib/default.nix
+++ b/pkgs/development/ocaml-modules/extlib/default.nix
@@ -1,5 +1,7 @@
 {stdenv, fetchurl, ocaml, findlib, minimal ? true}:
 
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.11";
+
 stdenv.mkDerivation {
   name = "ocaml-extlib-1.6.1";
 
diff --git a/pkgs/development/ocaml-modules/fix/default.nix b/pkgs/development/ocaml-modules/fix/default.nix
index 5ead575d0886..b0429e0e9103 100644
--- a/pkgs/development/ocaml-modules/fix/default.nix
+++ b/pkgs/development/ocaml-modules/fix/default.nix
@@ -1,5 +1,7 @@
 {stdenv, fetchurl, ocaml, findlib}:
 
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.12";
+
 stdenv.mkDerivation {
 
   name = "ocaml-fix-20130611";
@@ -17,7 +19,7 @@ stdenv.mkDerivation {
     homepage = http://gallium.inria.fr/~fpottier/fix/;
     description = "A simple OCaml module for computing the least solution of a system of monotone equations";
     license = licenses.cecill-c;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
-
diff --git a/pkgs/development/ocaml-modules/functory/default.nix b/pkgs/development/ocaml-modules/functory/default.nix
index b596272655e4..35dd542af9e3 100644
--- a/pkgs/development/ocaml-modules/functory/default.nix
+++ b/pkgs/development/ocaml-modules/functory/default.nix
@@ -1,5 +1,7 @@
 {stdenv, fetchurl, ocaml, findlib}:
 
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.11";
+
 stdenv.mkDerivation {
 
   name = "ocaml-functory-0.5";
@@ -19,8 +21,7 @@ stdenv.mkDerivation {
     homepage = https://www.lri.fr/~filliatr/functory/;
     description = "A distributed computing library for Objective Caml which facilitates distributed execution of parallelizable computations in a seamless fashion";
     license = licenses.lgpl21;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
-
-
diff --git a/pkgs/development/ocaml-modules/javalib/default.nix b/pkgs/development/ocaml-modules/javalib/default.nix
index 365fcc677cc9..fa55240caf2b 100644
--- a/pkgs/development/ocaml-modules/javalib/default.nix
+++ b/pkgs/development/ocaml-modules/javalib/default.nix
@@ -33,10 +33,11 @@ stdenv.mkDerivation rec {
 
   propagatedBuildInputs = [ camlzip extlib ];
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "A library that parses Java .class files into OCaml data structures";
     homepage = "${webpage}";
-    license = stdenv.lib.licenses.lgpl3;
+    license = licenses.lgpl3;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
diff --git a/pkgs/development/ocaml-modules/pprint/default.nix b/pkgs/development/ocaml-modules/pprint/default.nix
index e025801bb21c..18cc4817b130 100644
--- a/pkgs/development/ocaml-modules/pprint/default.nix
+++ b/pkgs/development/ocaml-modules/pprint/default.nix
@@ -1,5 +1,7 @@
 {stdenv, fetchurl, ocaml, findlib}:
 
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.12";
+
 stdenv.mkDerivation {
 
   name = "ocaml-pprint-20140424";
@@ -20,8 +22,7 @@ stdenv.mkDerivation {
     homepage = http://gallium.inria.fr/~fpottier/pprint/;
     description = "An OCaml adaptation of Wadler’s and Leijen’s prettier printer";
     license = licenses.cecill-c;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
-
-
diff --git a/pkgs/development/ocaml-modules/sawja/default.nix b/pkgs/development/ocaml-modules/sawja/default.nix
index ef3ab9a46b93..a464f93f65c6 100644
--- a/pkgs/development/ocaml-modules/sawja/default.nix
+++ b/pkgs/development/ocaml-modules/sawja/default.nix
@@ -1,4 +1,7 @@
 {stdenv, fetchurl, which, perl, ocaml, findlib, javalib }:
+
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.12";
+
 let
   pname = "sawja";
   version = "1.5";
@@ -26,10 +29,11 @@ stdenv.mkDerivation rec {
 
   propagatedBuildInputs = [ javalib ];
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "A library written in OCaml, relying on Javalib to provide a high level representation of Java bytecode programs";
     homepage = "${webpage}";
-    license = stdenv.lib.licenses.gpl3Plus;
+    license = licenses.gpl3Plus;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
diff --git a/pkgs/development/ocaml-modules/sqlite3EZ/default.nix b/pkgs/development/ocaml-modules/sqlite3EZ/default.nix
index e8ec8e6f5dac..94377a646c1c 100644
--- a/pkgs/development/ocaml-modules/sqlite3EZ/default.nix
+++ b/pkgs/development/ocaml-modules/sqlite3EZ/default.nix
@@ -1,5 +1,7 @@
 {stdenv, fetchurl, ocaml, findlib, twt, ocaml_sqlite3 }:
 
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.12";
+
 stdenv.mkDerivation {
   name = "ocaml-sqlite3EZ-0.1.0";
 
@@ -14,10 +16,11 @@ stdenv.mkDerivation {
 
   createFindlibDestdir = true;
 
-  meta = {
+  meta = with stdenv.lib; {
     homepage = http://github.com/mlin/ocaml-sqlite3EZ;
     description = "A thin wrapper for sqlite3-ocaml with a simplified interface";
-    license = stdenv.lib.licenses.mit;
+    license = licenses.mit;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
diff --git a/pkgs/development/ocaml-modules/twt/default.nix b/pkgs/development/ocaml-modules/twt/default.nix
index c06449f68b4c..0dc7170552ce 100644
--- a/pkgs/development/ocaml-modules/twt/default.nix
+++ b/pkgs/development/ocaml-modules/twt/default.nix
@@ -20,10 +20,11 @@ stdenv.mkDerivation {
 
   installFlags = "PREFIX=$(out)";
 
-  meta = {
+  meta = with stdenv.lib; {
     homepage = http://people.csail.mit.edu/mikelin/ocaml+twt/;
     description = "“The Whitespace Thing” for OCaml";
-    license = stdenv.lib.licenses.mit;
+    license = licenses.mit;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
diff --git a/pkgs/development/ocaml-modules/uucd/default.nix b/pkgs/development/ocaml-modules/uucd/default.nix
index 1d0f5c6cd504..476f0e9bbe8c 100644
--- a/pkgs/development/ocaml-modules/uucd/default.nix
+++ b/pkgs/development/ocaml-modules/uucd/default.nix
@@ -30,10 +30,11 @@ stdenv.mkDerivation rec {
 
   propagatedBuildInputs = [ xmlm ];
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "An OCaml module to decode the data of the Unicode character database from its XML representation";
     homepage = "${webpage}";
     platforms = ocaml.meta.platforms;
-    license = stdenv.lib.licenses.bsd3;
+    maintainers = [ maintainers.vbgl ];
+    license = licenses.bsd3;
   };
 }
diff --git a/pkgs/development/ocaml-modules/uunf/default.nix b/pkgs/development/ocaml-modules/uunf/default.nix
index c807bbd44637..ece5fb5e3e3f 100644
--- a/pkgs/development/ocaml-modules/uunf/default.nix
+++ b/pkgs/development/ocaml-modules/uunf/default.nix
@@ -5,6 +5,9 @@ let
   webpage = "http://erratique.ch/software/${pname}";
   ocaml_version = (builtins.parseDrvName ocaml.name).version;
 in
+
+assert stdenv.lib.versionAtLeast ocaml_version "3.12";
+
 stdenv.mkDerivation rec {
 
   name = "ocaml-${pname}-${version}";
@@ -28,10 +31,11 @@ stdenv.mkDerivation rec {
     ln -s $out/lib/${pname} $out/lib/ocaml/${ocaml_version}/site-lib/
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "An OCaml module for normalizing Unicode text";
     homepage = "${webpage}";
     platforms = ocaml.meta.platforms;
-    license = stdenv.lib.licenses.bsd3;
+    license = licenses.bsd3;
+    maintainers = [ maintainers.vbgl ];
   };
 }
diff --git a/pkgs/development/ocaml-modules/uutf/default.nix b/pkgs/development/ocaml-modules/uutf/default.nix
index 862236c169bc..26dc9742aeb4 100644
--- a/pkgs/development/ocaml-modules/uutf/default.nix
+++ b/pkgs/development/ocaml-modules/uutf/default.nix
@@ -5,6 +5,9 @@ let
   webpage = "http://erratique.ch/software/${pname}";
   ocaml_version = (builtins.parseDrvName ocaml.name).version;
 in
+
+assert stdenv.lib.versionAtLeast ocaml_version "3.12";
+
 stdenv.mkDerivation rec {
 
   name = "ocaml-${pname}-${version}";
@@ -28,10 +31,11 @@ stdenv.mkDerivation rec {
     ln -s $out/lib/${pname} $out/lib/ocaml/${ocaml_version}/site-lib/
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "Non-blocking streaming Unicode codec for OCaml";
     homepage = "${webpage}";
     platforms = ocaml.meta.platforms;
-    license = stdenv.lib.licenses.bsd3;
+    license = licenses.bsd3;
+    maintainers = [ maintainers.vbgl ];
   };
 }
diff --git a/pkgs/development/ocaml-modules/xmlm/default.nix b/pkgs/development/ocaml-modules/xmlm/default.nix
index bd19ab716f66..dacaeea49f4c 100644
--- a/pkgs/development/ocaml-modules/xmlm/default.nix
+++ b/pkgs/development/ocaml-modules/xmlm/default.nix
@@ -5,6 +5,9 @@ let
   webpage = "http://erratique.ch/software/${pname}";
   ocaml_version = (builtins.parseDrvName ocaml.name).version;
 in
+
+assert stdenv.lib.versionAtLeast ocaml_version "3.12";
+
 stdenv.mkDerivation rec {
 
   name = "ocaml-${pname}-${version}";
@@ -28,10 +31,11 @@ stdenv.mkDerivation rec {
     ln -s $out/lib/${pname} $out/lib/ocaml/${ocaml_version}/site-lib/
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "An OCaml streaming codec to decode and encode the XML data format";
     homepage = "${webpage}";
     platforms = ocaml.meta.platforms;
-    license = stdenv.lib.licenses.bsd3;
+    maintainers = [ maintainers.vbgl ];
+    license = licenses.bsd3;
   };
 }
diff --git a/pkgs/development/ocaml-modules/yojson/default.nix b/pkgs/development/ocaml-modules/yojson/default.nix
index 562d25550dae..0b40b68a7e83 100644
--- a/pkgs/development/ocaml-modules/yojson/default.nix
+++ b/pkgs/development/ocaml-modules/yojson/default.nix
@@ -25,10 +25,11 @@ stdenv.mkDerivation {
     mkdir $out/bin
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "An optimized parsing and printing library for the JSON format";
     homepage = "${webpage}";
-    license = stdenv.lib.licenses.bsd3;
+    license = licenses.bsd3;
+    maintainers = [ maintainers.vbgl ];
     platforms = ocaml.meta.platforms;
   };
 }
diff --git a/pkgs/development/tools/ocaml/cppo/default.nix b/pkgs/development/tools/ocaml/cppo/default.nix
index 04475959f3d9..49a63b616c75 100644
--- a/pkgs/development/tools/ocaml/cppo/default.nix
+++ b/pkgs/development/tools/ocaml/cppo/default.nix
@@ -4,6 +4,7 @@ let
   version = "0.9.4";
   webpage = "http://mjambon.com/${pname}.html";
 in
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.12";
 stdenv.mkDerivation rec {
 
   name = "${pname}-${version}";
@@ -23,15 +24,13 @@ stdenv.mkDerivation rec {
     mkdir $out/bin
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "The C preprocessor for OCaml";
     longDescription = ''
       Cppo is an equivalent of the C preprocessor targeted at the OCaml language and its variants.
     '';
     homepage = "${webpage}";
-    license = "bsd";
+    maintainers = [ maintainers.vbgl ];
+    license = licenses.bsd3;
   };
 }
-
-
-
diff --git a/pkgs/development/tools/ocaml/merlin/default.nix b/pkgs/development/tools/ocaml/merlin/default.nix
index 623b84bafd1d..30fabf193620 100644
--- a/pkgs/development/tools/ocaml/merlin/default.nix
+++ b/pkgs/development/tools/ocaml/merlin/default.nix
@@ -1,4 +1,7 @@
 {stdenv, fetchurl, ocaml, findlib, yojson, menhir}:
+
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "4.00";
+
 stdenv.mkDerivation {
 
   name = "merlin-1.7.1";
@@ -12,10 +15,10 @@ stdenv.mkDerivation {
 
   prefixKey = "--prefix ";
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "An editor-independent tool to ease the development of programs in OCaml";
     homepage = "http://the-lambda-church.github.io/merlin/";
-    license = stdenv.lib.licenses.mit;
+    license = licenses.mit;
+    maintainers = [ maintainers.vbgl ];
   };
 }
-
diff --git a/pkgs/development/tools/ocaml/opam/1.0.0.nix b/pkgs/development/tools/ocaml/opam/1.0.0.nix
index 4c74063d1165..52c710a86b82 100644
--- a/pkgs/development/tools/ocaml/opam/1.0.0.nix
+++ b/pkgs/development/tools/ocaml/opam/1.0.0.nix
@@ -1,5 +1,7 @@
 { stdenv, fetchgit, fetchurl, ocaml, unzip, ncurses, curl }:
 
+assert stdenv.lib.versionAtLeast (stdenv.lib.getVersion ocaml) "3.12.1";
+
 let
   srcs = {
     cudf = fetchurl {
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 9947c6642ad8..3bbeeb96db16 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -3502,10 +3502,6 @@ let
 
     pycaml = callPackage ../development/ocaml-modules/pycaml { };
 
-    opam_1_0_0 = callPackage ../development/tools/ocaml/opam/1.0.0.nix { };
-    opam_1_1 = callPackage ../development/tools/ocaml/opam/1.1.nix { };
-    opam = opam_1_1;
-
     sqlite3EZ = callPackage ../development/ocaml-modules/sqlite3EZ { };
 
     twt = callPackage ../development/ocaml-modules/twt { };
@@ -3543,6 +3539,10 @@ let
 
   opa = let callPackage = newScope pkgs.ocamlPackages_4_00_1; in callPackage ../development/compilers/opa { };
 
+  opam_1_0_0 = callPackage ../development/tools/ocaml/opam/1.0.0.nix { };
+  opam_1_1 = callPackage ../development/tools/ocaml/opam/1.1.nix { };
+  opam = opam_1_1;
+
   ocamlnat = let callPackage = newScope pkgs.ocamlPackages_3_12_1; in callPackage ../development/ocaml-modules/ocamlnat { };
 
   qcmm = callPackage ../development/compilers/qcmm {