diff --git a/crates/typst-library/src/model/figure.rs b/crates/typst-library/src/model/figure.rs
index e871fbeb8..fd843ee53 100644
--- a/crates/typst-library/src/model/figure.rs
+++ b/crates/typst-library/src/model/figure.rs
@@ -308,6 +308,7 @@ impl Synthesize for Packed<FigureElem> {
         // Fill the figure's caption.
         let mut caption = elem.caption(styles);
         if let Some(caption) = &mut caption {
+            caption.synthesize(engine, styles)?;
             caption.push_kind(kind.clone());
             caption.push_supplement(supplement.clone());
             caption.push_numbering(numbering.clone());
diff --git a/tests/ref/issue-5370-figure-caption-separator-outline.png b/tests/ref/issue-5370-figure-caption-separator-outline.png
new file mode 100644
index 000000000..a9b0d06e1
Binary files /dev/null and b/tests/ref/issue-5370-figure-caption-separator-outline.png differ
diff --git a/tests/suite/model/figure.typ b/tests/suite/model/figure.typ
index 58ba2b2a4..0e5db4d07 100644
--- a/tests/suite/model/figure.typ
+++ b/tests/suite/model/figure.typ
@@ -289,3 +289,9 @@ HI#footnote.entry(clearance: 2.5em)[There]
 )
 
 #c
+
+--- issue-5370-figure-caption-separator-outline ---
+// Test that language-dependant caption separator is respected in outline.
+#outline(title: none, target: figure)
+#set text(lang: "ru")
+#figure(rect(), caption: [Rectangle])