diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3758f1d1..926b128f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@ Unreleased
 ----------
 - Enabled usage of empty PWS slot fields
 - Changed error reporting format to make up only a single line
-- Added the `pws add` subcommand to write to the first unprogrammed slot
+- Added the `pws add` subcommand to write to a new slot
 - Added the `pws update` subcommand to update an existing PWS slot
 - Added the `--only-aes-key` option to the `reset` command to build a new AES
   key without performing a factory reset
diff --git a/doc/nitrocli.1 b/doc/nitrocli.1
index 24bff555..14cf0490 100644
--- a/doc/nitrocli.1
+++ b/doc/nitrocli.1
@@ -1,4 +1,4 @@
-.TH NITROCLI 1 2021-04-17
+.TH NITROCLI 1 2021-04-18
 .SH NAME
 nitrocli \- access Nitrokey devices
 .SH SYNOPSIS
@@ -279,10 +279,13 @@ Set the content of a PWS slot.
 \fIname\fR, \fIlogin\fR, and \fIpassword\fR represent the data to write to the
 slot.
 .TP
-\fBnitrocli pws add \fIslot name login password\fR
+\fBnitrocli pws add \fR[\fB\-s\fR|\fB\-\-slot \fIslot\fR] \
+\fIname login password\fR
 Add a new PWS slot.
-This command locates the first free PWS slot and sets its content to the given
-values.
+If the \fB\-\-slot\fR option is set, this command writes the data to the given
+slot and fails if the slot is already programmed.
+If the \fB\-\-slot\fR option is not set, this command locates the first free
+PWS slot and sets its content to the given values.
 It fails if all PWS slots are programmed.
 .TP
 \fBnitrocli pws update \fIslot\fR \
diff --git a/doc/nitrocli.1.pdf b/doc/nitrocli.1.pdf
index 5cd6baaf..bf761f6b 100644
Binary files a/doc/nitrocli.1.pdf and b/doc/nitrocli.1.pdf differ
diff --git a/src/args.rs b/src/args.rs
index b9a85789..dc6bcea0 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -398,9 +398,9 @@ Command! {PwsCommand, [
   Set(PwsSetArgs) => |ctx, args: PwsSetArgs| {
     crate::commands::pws_set(ctx, args.slot, &args.name, &args.login, &args.password)
   },
-  /// Writes data to the first free password safe slot
+  /// Adds a new password safe slot
   Add(PwsAddArgs) => |ctx, args: PwsAddArgs| {
-    crate::commands::pws_add(ctx, &args.name, &args.login, &args.password)
+    crate::commands::pws_add(ctx, &args.name, &args.login, &args.password, args.slot)
   },
   /// Updates a password safe slot
   Update(PwsUpdateArgs) => |ctx, args: PwsUpdateArgs| {
@@ -460,6 +460,11 @@ pub struct PwsAddArgs {
   pub login: String,
   /// The password to store on the slot
   pub password: String,
+  /// The number of the slot to write
+  ///
+  /// If this option is not set, the first unprogrammed slot is used.
+  #[structopt(short, long)]
+  pub slot: Option<u8>,
 }
 
 #[derive(Debug, PartialEq, structopt::StructOpt)]
diff --git a/src/commands.rs b/src/commands.rs
index 9d54e592..18206b19 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -1047,25 +1047,48 @@ pub fn pws_set(
   })
 }
 
-/// Write data to the first unprogrammed PWS slot.
+/// Add a new PWS slot.
 pub fn pws_add(
   ctx: &mut Context<'_>,
   name: &str,
   login: &str,
   password: &str,
+  slot_idx: Option<u8>,
 ) -> anyhow::Result<()> {
   with_password_safe(ctx, |ctx, mut pws| {
     let slots = pws.get_slots()?;
-    if let Some(slot) = slots.iter().position(Option::is_none) {
-      let slot = u8::try_from(slot).context("Unexpected number of password slots")?;
-      pws
-        .write_slot(slot, name, login, password)
-        .context("Failed to write PWS slot")?;
-      println!(ctx, "Added PWS slot {}", slot)?;
-      Ok(())
+
+    let slot_idx = if let Some(slot_idx) = slot_idx {
+      // If the user specified a slot, make sure that it is not programmed
+      if let Some(slot) = slots.get(usize::from(slot_idx)) {
+        if slot.is_some() {
+          Err(anyhow::anyhow!(
+            "The PWS slot {} is already programmed",
+            slot_idx
+          ))
+        } else {
+          Ok(slot_idx)
+        }
+      } else {
+        Err(anyhow::anyhow!(
+          "Encountered invalid slot index: {}",
+          slot_idx
+        ))
+      }
     } else {
-      Err(anyhow::anyhow!("All PWS slots are already programmed"))
-    }
+      // If the user did not specify a slot, we try to find the first unprogrammed slot
+      if let Some(slot_idx) = slots.iter().position(Option::is_none) {
+        u8::try_from(slot_idx).context("Unexpected number of PWS slots")
+      } else {
+        Err(anyhow::anyhow!("All PWS slots are already programmed"))
+      }
+    }?;
+
+    pws
+      .write_slot(slot_idx, name, login, password)
+      .context("Failed to write PWS slot")?;
+    println!(ctx, "Added PWS slot {}", slot_idx)?;
+    Ok(())
   })
 }
 
diff --git a/src/tests/pws.rs b/src/tests/pws.rs
index b01e127f..68dde9e6 100644
--- a/src/tests/pws.rs
+++ b/src/tests/pws.rs
@@ -29,6 +29,17 @@ fn set_invalid_slot(model: nitrokey::Model) {
   assert_eq!(err, "Failed to write PWS slot");
 }
 
+#[test_device]
+fn add_invalid_slot(model: nitrokey::Model) {
+  let err = Nitrocli::new()
+    .model(model)
+    .handle(&["pws", "add", "--slot", "100", "name", "login", "1234"])
+    .unwrap_err()
+    .to_string();
+
+  assert_eq!(err, "Encountered invalid slot index: 100");
+}
+
 #[test_device]
 fn status(model: nitrokey::Model) -> anyhow::Result<()> {
   let re = regex::Regex::new(
@@ -227,6 +238,43 @@ fn add_full(model: nitrokey::Model) -> anyhow::Result<()> {
   Ok(())
 }
 
+#[test_device]
+fn add_existing(model: nitrokey::Model) -> anyhow::Result<()> {
+  let mut ncli = Nitrocli::new().model(model);
+
+  // Fill slot 0
+  let _ = ncli.handle(&["pws", "set", "0", "name0", "login0", "pass0rd"])?;
+
+  // Try to add slot 0
+  let res = ncli.handle(&["pws", "add", "--slot", "0", "name", "login", "passw0rd"]);
+
+  let err = res.unwrap_err().to_string();
+  assert_eq!(err, "The PWS slot 0 is already programmed");
+  Ok(())
+}
+
+#[test_device]
+fn add_slot(model: nitrokey::Model) -> anyhow::Result<()> {
+  let mut ncli = Nitrocli::new().model(model);
+
+  // Fill slots 0 and 5
+  let _ = ncli.handle(&["pws", "set", "0", "name0", "login0", "passw0rd"])?;
+  let _ = ncli.handle(&["pws", "set", "5", "name5", "login5", "passw5rd"])?;
+
+  // Clear slot 1 (in case it was written to by other slots)
+  let _ = ncli.handle(&["pws", "clear", "1"])?;
+
+  // Try to add slot 1
+  let out = ncli.handle(&["pws", "add", "--slot", "1", "name1", "login1", "passw1rd"])?;
+  assert_eq!("Added PWS slot 1\n", out);
+
+  assert_slot(model, 0, "name0", "login0", "passw0rd")?;
+  assert_slot(model, 1, "name1", "login1", "passw1rd")?;
+  assert_slot(model, 5, "name5", "login5", "passw5rd")?;
+
+  Ok(())
+}
+
 #[test_device]
 fn add(model: nitrokey::Model) -> anyhow::Result<()> {
   let mut ncli = Nitrocli::new().model(model);