diff --git a/packages/mirage-unikernel-hello-hvt.0.0.2/opam b/packages/mirage-unikernel-hello-hvt.0.0.2/opam
index 62f9577..e796bd8 100644
--- a/packages/mirage-unikernel-hello-hvt.0.0.2/opam
+++ b/packages/mirage-unikernel-hello-hvt.0.0.2/opam
@@ -8,7 +8,7 @@ bug-reports: "dummy"
 dev-repo: "git://dummy"
 synopsis: "The famous hello world unikernel"
 
-build: ["sh" "-exc" "cd tutorial/hello-key/ && mirage build"]
+build: [make "-Ctutorial/hello-key/" "build"]
 
 install: [
   [ "cp" "tutorial/hello-key/dist/hello-key.hvt" "%{bin}%/hello-key.hvt" ]
diff --git a/packages/mirage-unikernel-qubes-firewall-xen.0.0.2/opam b/packages/mirage-unikernel-qubes-firewall-xen.0.0.2/opam
index 854fa84..d4c18f9 100644
--- a/packages/mirage-unikernel-qubes-firewall-xen.0.0.2/opam
+++ b/packages/mirage-unikernel-qubes-firewall-xen.0.0.2/opam
@@ -8,7 +8,7 @@ bug-reports: "dummy"
 dev-repo: "git://dummy"
 synopsis: "A QubesOS firewall as unikernel"
 
-build: ["sh" "-exc" "mirage build"]
+build: [make "build"]
 
 install: [
   [ "cp" "dist/qubes-firewall.xen" "%{bin}%/qubes-firewall.xen" ]
diff --git a/packages/mirage-unikernel-static-website-hvt.0.0.2/opam b/packages/mirage-unikernel-static-website-hvt.0.0.2/opam
index 5fa823a..152e696 100644
--- a/packages/mirage-unikernel-static-website-hvt.0.0.2/opam
+++ b/packages/mirage-unikernel-static-website-hvt.0.0.2/opam
@@ -8,7 +8,7 @@ bug-reports: "dummy"
 dev-repo: "git://dummy"
 synopsis: "A static website example unikernel"
 
-build: ["sh" "-exc" "cd applications/static_website_tls/ && mirage build"]
+build: [make "-Capplications/static_website_tls/" "build"]
 
 install: [
   [ "cp" "applications/static_website_tls/dist/https.hvt" "%{bin}%/https.hvt" ]