diff --git a/src/constants.rs b/src/constants.rs
index d160387..4ca67ef 100644
--- a/src/constants.rs
+++ b/src/constants.rs
@@ -2,5 +2,5 @@
 pub const BUSY_WAIT_TIME: std::time::Duration = std::time::Duration::from_secs(5);
 
 // The location of the keys DB relative to the user's home directory.
-pub const KEYS_DB: &[ &str ] = &[ ".pEp", "keys.db" ];
+pub const KEYS_DB: &[ &str ] = &[ "keys.db" ];
 
diff --git a/src/keystore.rs b/src/keystore.rs
index e826f69..90d4f3f 100644
--- a/src/keystore.rs
+++ b/src/keystore.rs
@@ -1,5 +1,6 @@
 use std::cmp;
 use std::env;
+use std::path::Path;
 use std::path::PathBuf;
 
 use rusqlite::{
@@ -157,8 +158,10 @@ impl Keystore {
     /// Initializes the key store.
     ///
     /// This opens the keys.db and initializes it, if necessary.
-    pub fn init() -> Result<Self> {
-        Self::init_(false)
+    pub fn init<P>(dir: P) -> Result<Self>
+        where P: AsRef<Path>
+    {
+        Self::init_(Some(dir.as_ref()))
     }
 
     /// Initializes an in-memory key store.
@@ -166,45 +169,22 @@ impl Keystore {
     /// This is used for the unit tests.
     #[cfg(test)]
     pub(crate) fn init_in_memory() -> Result<Self> {
-        Self::init_(true)
+        Self::init_(None)
     }
 
-    fn init_(in_memory: bool) -> Result<Self> {
-        let keys_db = PathBuf::new();
+    fn init_(home: Option<&Path>) -> Result<Self> {
+        let mut keys_db = PathBuf::new();
 
-        let conn = if in_memory {
-            wrap_err!(
-                Connection::open_in_memory(),
-                InitCannotOpenDB,
-                "Creating in-memory keys DB")?
-        } else {
-            let mut home: Option<PathBuf> = None;
+        let conn = if let Some(home) = home {
+            keys_db.push(home);
 
-            // Create the home directory.
             #[cfg(not(windows))]
-            {
-                if cfg!(debug_assertions) {
-                    home = env::var("PEP_HOME").ok().map(|s| PathBuf::from(s));
-                }
-                #[allow(deprecated)]
-                if home.is_none() {
-                    home = env::home_dir();
+            if cfg!(debug_assertions) {
+                if let Ok(pep_home) = env::var("PEP_HOME") {
+                    keys_db = PathBuf::from(pep_home);
                 }
             }
 
-            #[cfg(windows)]
-            {
-                // Get the home directory on Windows.
-                unimplemented!();
-            }
-
-            let home = match home {
-                None => return Err(Error::InitCryptoLibInitFailed(
-                    "HOME environment variable unset".into()).into()),
-                Some(home) => home,
-            };
-
-            let mut keys_db = home;
             for n in KEYS_DB {
                 keys_db.push(n);
             }
@@ -218,6 +198,12 @@ impl Keystore {
                         | OpenFlags::SQLITE_OPEN_PRIVATE_CACHE),
                 InitCannotOpenDB,
                 format!("Opening keys DB ('{}')", keys_db.display()))?
+        } else {
+            // Create an in-memory DB.
+            wrap_err!(
+                Connection::open_in_memory(),
+                InitCannotOpenDB,
+                "Creating in-memory keys DB")?
         };
 
         wrap_err!(
diff --git a/src/lib.rs b/src/lib.rs
index cc1afa9..ba8043e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,12 +1,16 @@
 use std::cmp;
 use std::convert::TryInto;
 use std::env;
-use std::ffi::CStr;
+use std::ffi::{
+    CStr,
+    OsStr,
+};
 use std::io::{
     Read,
     Write,
 };
 use std::mem;
+use std::path::Path;
 use std::ptr;
 use std::slice;
 use std::time::{
@@ -197,6 +201,7 @@ fn _pgp_get_decrypted_key_iter<'a, I>(iter: I, pass: Option<&Password>)
 
 // PEP_STATUS pgp_init(PEP_SESSION session, bool in_first)
 ffi!(fn pgp_init_(session: *mut Session, _in_first: bool,
+                  per_user_directory: *const c_char,
                   session_size: c_uint,
                   session_cookie_offset: c_uint,
                   session_curr_passphrase_offset: c_uint,
@@ -241,7 +246,27 @@ ffi!(fn pgp_init_(session: *mut Session, _in_first: bool,
 
     let session = Session::as_mut(session);
 
-    let ks = keystore::Keystore::init()?;
+    if per_user_directory.is_null() {
+        return Err(Error::IllegalValue(
+            "per_user_directory may not be NULL".into()));
+    }
+    let per_user_directory = unsafe { CStr::from_ptr(per_user_directory) };
+
+    #[cfg(not(windows))]
+    let per_user_directory = {
+        use std::os::unix::ffi::OsStrExt;
+        OsStr::from_bytes(per_user_directory.to_bytes())
+    };
+    #[cfg(windows)]
+    let per_user_directory = {
+        use std::ffi::OsString;
+        use std::os::windows::prelude::*;
+
+        let os_string = OsString::from_wide(per_user_directory.as_bytes());
+        os_string.as_os_str()
+    };
+
+    let ks = keystore::Keystore::init(Path::new(per_user_directory))?;
     session.set_keystore(ks);
 
     Ok(())