diff --git a/opam b/opam
index 200a3ca..c702c70 100644
--- a/opam
+++ b/opam
@@ -12,6 +12,7 @@ available:     [ ocaml-version >= "4.02.0" ]
 build: ["ocaml" "pkg/pkg.ml" "build" "--pinned" "%{pinned}%" "--tests" "false"
                 "--with-lwt" "%{lwt:installed}%"
                 "--xen" "%{mirage-xen:installed}%"
+                "--mirage" "%{mirage-entropy:installed}%"
                 "--freestanding" "%{mirage-solo5:installed}%"]
 
 depends: [
@@ -28,14 +29,15 @@ depends: [
   "zarith"
   "lwt"
   "sexplib"
-  ("mirage-no-xen" | ("mirage-xen" & "mirage-entropy" & "zarith-xen"))
-  ("mirage-no-solo5" | ("mirage-solo5" & "mirage-entropy" & "zarith-freestanding"))
+  ("mirage-no-xen" | ("mirage-xen" & "zarith-xen"))
+  ("mirage-no-solo5" | ("mirage-solo5" & "zarith-freestanding"))
 ]
 
+depopts: ["mirage-entropy"]
+
 conflicts: [
   "topkg" {<"0.8.0"}
   "ocb-stubblr" {<"0.1.0"}
   "mirage-xen" {<"2.2.0"}
   "sexplib" {="v0.9.0"}
 ]
-
diff --git a/pkg/pkg.ml b/pkg/pkg.ml
index e0082f3..ff7654c 100755
--- a/pkg/pkg.ml
+++ b/pkg/pkg.ml
@@ -15,6 +15,8 @@ let xen  = Conf.(key "xen" bool ~absent:false
                  ~doc:"Build Mirage/Xen support.")
 let fs   = Conf.(key "freestanding" bool ~absent:false
                  ~doc:"Build Mirage/Solo5 support.")
+let mir  = Conf.(key "mirage" bool ~absent:false
+                  ~doc:"Build Mirage support.")
 let accelerate = Conf.(discovered_key "accelerate" bool
   ~absent:cpudetect
   ~env:"NOCRYPTO_ACCELERATE"
@@ -40,11 +42,12 @@ let () =
     let lwt  = Conf.value c lwt && unix
     and xen  = Conf.value c xen
     and fs   = Conf.value c fs in
+    let mir  = Conf.value c mir in
     Ok [ Pkg.clib "src/libnocrypto_stubs.clib";
          Pkg.mllib "src/nocrypto.mllib";
          Pkg.mllib ~cond:unix "unix/nocrypto_unix.mllib";
          Pkg.mllib ~cond:lwt "lwt/nocrypto_lwt.mllib";
-         Pkg.mllib ~cond:(xen||fs) "mirage/nocrypto_mirage.mllib";
+         Pkg.mllib ~cond:mir "mirage/nocrypto_mirage.mllib";
          Pkg.test "tests/testrunner";
          Pkg.test ~run:false "bench/speed";
          mirage ~xen ~fs "src/libnocrypto_stubs.clib"; ]