diff --git a/crates/engine/src/cmd/blocks.rs b/crates/engine/src/cmd/blocks.rs
--- a/crates/engine/src/cmd/blocks.rs
+++ b/crates/engine/src/cmd/blocks.rs
@@ -341,6 +341,10 @@ fn run_wblock(s: &mut Session, p: &Value) -> Result<Value> {
     d.text_styles = src.text_styles.clone();
     d.dim_styles = src.dim_styles.clone();
     d.blocks = src.blocks.clone();
+    // The written drawing keeps the source's units, as AutoCAD's -WBLOCK does: a block written from
+    // a metric drawing is not declared in inches, which would scale it on insert into such a file.
+    d.header.set_i64("INSUNITS", src.header.i64("INSUNITS", 1));
+    d.header.set_i64("MEASUREMENT", src.header.i64("MEASUREMENT", 0));
     // The base point becomes the written drawing's origin, its insertion base: by default 0,0 for
     // objects and the block's base point for a block (`base` is then in block coordinates).
     let base = point_param(p, "base");
diff --git a/crates/engine/tests/wblock_units.rs b/crates/engine/tests/wblock_units.rs
new file mode 100644
--- /dev/null
+++ b/crates/engine/tests/wblock_units.rs
@@ -0,0 +1,50 @@
+//! WBLOCK writes the source drawing's units: `$INSUNITS` and `$MEASUREMENT` of the written file
+//! are the source's, for selected objects and for a block, as AutoCAD's `-WBLOCK` does.
+
+use cadcraft_engine::Session;
+use cadcraft_engine::cmd::file::{IoHooks, set_io};
+use cadcraft_engine::doc::Drawing;
+use serde_json::json;
+
+/// Writes "INSUNITS;MEASUREMENT" so the test can read the units of the file that would be saved.
+fn write(d: &Drawing, _path: &str) -> Result<Vec<u8>, String> {
+    Ok(format!("{};{}", d.header.i64("INSUNITS", -1), d.header.i64("MEASUREMENT", -1)).into_bytes())
+}
+
+fn written(s: &mut Session, p: serde_json::Value) -> String {
+    let path = std::env::temp_dir().join(format!("cadcraft-wblock-units-{}.dxf", std::process::id()));
+    let mut p = p;
+    p["path"] = json!(path.to_string_lossy());
+    s.execute("wblock", &p).unwrap();
+    let text = std::fs::read_to_string(&path).unwrap();
+    let _ = std::fs::remove_file(&path);
+    text
+}
+
+fn line(s: &mut Session) -> String {
+    s.execute("line", &json!({ "points": [[0, 0], [2, 0]] })).unwrap()["handles"][0].as_str().unwrap().to_string()
+}
+
+#[test]
+fn wblock_keeps_the_source_drawing_units() {
+    set_io(IoHooks { read: |_, _| Err("no reader in this test".into()), write, plot: None });
+    let mut s = Session::new();
+    // A metric drawing in metres, like the issue's metres.dxf (`--metric` then `insunits 6`).
+    s.new_drawing(true);
+    s.execute("units", &json!({ "insunits": 6 })).unwrap();
+    let b = line(&mut s);
+    s.execute("block", &json!({ "name": "B", "base": [0, 0], "handles": [b], "keep": "delete" })).unwrap();
+    let c = line(&mut s);
+
+    // Selected objects and a block by name both keep the source's units, not inches.
+    assert_eq!(written(&mut s, json!({ "handles": [c] })), "6;1");
+    assert_eq!(written(&mut s, json!({ "name": "B" })), "6;1");
+
+    // The metric default (millimetres) and an imperial drawing keep their units too.
+    s.new_drawing(true);
+    let m = line(&mut s);
+    assert_eq!(written(&mut s, json!({ "handles": [m] })), "4;1");
+    s.new_drawing(false);
+    let i = line(&mut s);
+    assert_eq!(written(&mut s, json!({ "handles": [i] })), "1;0");
+}