diff --git a/README.md b/README.md
index f3fe4a9..6822a44 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,19 @@ DKIM filter for [OpenSMTPD](https://www.opensmtpd.org/).
 This is a work in progress, it is not supposed to work yet.
 
 
+## Building and packaging
+
+```
+cargo build --release
+```
+
+Packagers may want to set the `VARLIBDIR` to a custom value (default is `/var/lib`):
+
+```
+VARLIBDIR="/usr/local/var/lib" cargo build --release
+```
+
+
 ## Frequently Asked Questions
 
 ### Does this filter signs outgoing emails using DKIM or check the DKIM signature of incoming emails?
diff --git a/build.rs b/build.rs
new file mode 100644
index 0000000..78a4e6e
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,9 @@
+use std::env;
+
+const DEFAULT_VARLIBDIR: &str = "/var/lib/";
+
+fn main() {
+	if let Err(_) = env::var("VARLIBDIR") {
+		println!("cargo:rustc-env={}={}", "VARLIBDIR", DEFAULT_VARLIBDIR);
+	}
+}
diff --git a/src/config.rs b/src/config.rs
index dd659ea..c1df822 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -109,6 +109,7 @@ fn process_key_data_base(opt: Option<PathBuf>) -> Option<PathBuf> {
 		Some(p) => Some(p),
 		None => {
 			let mut path = PathBuf::from(crate::DEFAULT_LIB_DIR);
+			path.push(env!("CARGO_PKG_NAME"));
 			path.push(crate::DEFAULT_CNF_KEY_DB);
 			Some(path)
 		}
diff --git a/src/main.rs b/src/main.rs
index e5c5f04..0b2380a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -24,7 +24,7 @@ const DEFAULT_CNF_HEADERS: &str = "from:reply-to:subject:date:to:cc";
 const DEFAULT_CNF_HEADERS_OPT: &str = "resent-date:resent-from:resent-to:resent-cc:in-reply-to:references:list-id:list-help:list-unsubscribe:list-subscribe:list-post:list-owner:list-archive";
 const DEFAULT_CNF_KEY_DB: &str = "key-db.sqlite3";
 const DEFAULT_CNF_REVOCATION: u64 = 1728000;
-const DEFAULT_LIB_DIR: &str = "/var/lib/opensmtpd-filter-dkimout";
+const DEFAULT_LIB_DIR: &str = env!("VARLIBDIR");
 const DEFAULT_MSG_SIZE: usize = 1024 * 1024;
 const LOG_LEVEL_ENV_VAR: &str = "OPENSMTPD_FILTER_DKIMOUT_LOG_LEVEL";