diff --git a/pkgs/development/compilers/obliv-c/default.nix b/pkgs/development/compilers/obliv-c/default.nix
index 3e13b9247fb9..f2eadee57937 100644
--- a/pkgs/development/compilers/obliv-c/default.nix
+++ b/pkgs/development/compilers/obliv-c/default.nix
@@ -7,6 +7,7 @@ stdenv.mkDerivation rec {
   strictDeps = true;
   nativeBuildInputs = [ perl ]
   ++ (with ocamlPackages; [ ocaml findlib ocamlbuild ]);
+  buildInputs = [ ocamlPackages.num ];
   propagatedBuildInputs = [ libgcrypt ];
   src = fetchFromGitHub {
     owner = "samee";
@@ -19,6 +20,9 @@ stdenv.mkDerivation rec {
 
   patches = [ ./ignore-complex-float128.patch ];
 
+  # https://github.com/samee/obliv-c/issues/76#issuecomment-438958209
+  env.OCAMLBUILD = "ocamlbuild -package num -ocamlopt 'ocamlopt -dontlink num' -ocamlc 'ocamlc -dontlink num'";
+
   preBuild = ''
     patchShebangs .
   '';
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 8086a44fe793..85ba768df5a7 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -15529,8 +15529,10 @@ with pkgs;
 
   nvidia_cg_toolkit = callPackage ../development/compilers/nvidia-cg-toolkit { };
 
-  obliv-c = callPackage ../development/compilers/obliv-c
-    { stdenv = gcc10StdenvCompat; ocamlPackages = ocaml-ng.ocamlPackages_4_05; };
+  obliv-c = callPackage ../development/compilers/obliv-c {
+    stdenv = gcc10StdenvCompat;
+    ocamlPackages = ocaml-ng.ocamlPackages_4_14;
+  };
 
   ocaml-ng = callPackage ./ocaml-packages.nix { };
   ocaml = ocamlPackages.ocaml;