diff --git a/milli/src/update/delete_documents.rs b/milli/src/update/delete_documents.rs
index 2b67535c9..932589dd7 100644
--- a/milli/src/update/delete_documents.rs
+++ b/milli/src/update/delete_documents.rs
@@ -1,6 +1,8 @@
+use anyhow::anyhow;
 use fst::IntoStreamer;
 use heed::types::ByteSlice;
 use roaring::RoaringBitmap;
+use serde_json::Value;
 
 use crate::facet::FacetType;
 use crate::{Index, BEU32, SmallString32, ExternalDocumentsIds};
@@ -95,7 +97,11 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
             let mut iter = documents.range_mut(self.wtxn, &(key..=key))?;
             if let Some((_key, obkv)) = iter.next().transpose()? {
                 if let Some(content) = obkv.get(id_field) {
-                    let external_id: SmallString32 = serde_json::from_slice(content).unwrap();
+                    let external_id = match serde_json::from_slice(content).unwrap() {
+                        Value::String(string) => SmallString32::from(string.as_str()),
+                        Value::Number(number) => SmallString32::from(number.to_string()),
+                        _ => return Err(anyhow!("documents ids must be either strings or numbers")),
+                    };
                     external_ids.push(external_id);
                 }
                 iter.del_current()?;
@@ -248,3 +254,39 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
         Ok(self.documents_ids.len() as usize)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use heed::EnvOpenOptions;
+
+    use crate::update::{IndexDocuments, UpdateFormat};
+    use super::*;
+
+    #[test]
+    fn delete_documents_with_numbers_as_primary_key() {
+        let path = tempfile::tempdir().unwrap();
+        let mut options = EnvOpenOptions::new();
+        options.map_size(10 * 1024 * 1024); // 10 MB
+        let index = Index::new(options, &path).unwrap();
+
+        // First we send 3 documents with an id for only one of them.
+        let mut wtxn = index.write_txn().unwrap();
+        let content = &br#"[
+            { "id": 0, "name": "kevin", "object": { "key1": "value1", "key2": "value2" } },
+            { "id": 1, "name": "kevina", "array": ["I", "am", "fine"] },
+            { "id": 2, "name": "benoit", "array_of_object": [{ "wow": "amazing" }] }
+        ]"#[..];
+        let mut builder = IndexDocuments::new(&mut wtxn, &index, 0);
+        builder.update_format(UpdateFormat::Json);
+        builder.execute(content, |_, _| ()).unwrap();
+
+        // delete those documents, ids are synchronous therefore 0, 1, and 2.
+        let mut builder = DeleteDocuments::new(&mut wtxn, &index, 1).unwrap();
+        builder.delete_document(0);
+        builder.delete_document(1);
+        builder.delete_document(2);
+        builder.execute().unwrap();
+
+        wtxn.commit().unwrap();
+    }
+}
diff --git a/milli/src/update/index_documents/transform.rs b/milli/src/update/index_documents/transform.rs
index d53b83361..68888aad9 100644
--- a/milli/src/update/index_documents/transform.rs
+++ b/milli/src/update/index_documents/transform.rs
@@ -178,16 +178,10 @@ impl Transform<'_, '_> {
                     serde_json::to_writer(&mut json_buffer, value)?;
                     writer.insert(field_id, &json_buffer)?;
                 }
-                else if field_id == primary_key_id {
-                    // We validate the document id [a-zA-Z0-9\-_].
-                    let external_id = match validate_document_id(&external_id) {
-                        Some(valid) => valid,
-                        None => return Err(anyhow!("invalid document id: {:?}", external_id)),
-                    };
 
-                    // We serialize the document id.
-                    serde_json::to_writer(&mut json_buffer, &external_id)?;
-                    writer.insert(field_id, &json_buffer)?;
+                // We validate the document id [a-zA-Z0-9\-_].
+                if field_id == primary_key_id && validate_document_id(&external_id).is_none() {
+                    return Err(anyhow!("invalid document id: {:?}", external_id));
                 }
             }