diff --git a/build/pkg-libs.sh b/build/pkg-libs.sh
index 6fd484c..e2d48ef 100755
--- a/build/pkg-libs.sh
+++ b/build/pkg-libs.sh
@@ -5,7 +5,7 @@ set -e
 # Shard directory passed as first argument when called from lib_sodium.cr
 [ ! -z "$1" ] && cd "$1"
 
-./build/libsodium_install.sh > libsodium_install.out 2>&1
+./build/libsodium_install.sh > libsodium_install.out 2>&1 || (cat libsodium_install.out >&2 ; exit 2)
 
 . ./build/env.sh
 
diff --git a/shard.yml b/shard.yml
index 8704106..e0568e8 100644
--- a/shard.yml
+++ b/shard.yml
@@ -11,3 +11,5 @@ targets:
 libraries:
   libsodium: ">= 1.0.18"
 license: MIT
+scripts:
+  postinstall: ./build/libsodium_install.sh