diff --git a/crates/typst/src/math/equation.rs b/crates/typst/src/math/equation.rs
index eb8f8f66..c5cb9132 100644
--- a/crates/typst/src/math/equation.rs
+++ b/crates/typst/src/math/equation.rs
@@ -176,6 +176,8 @@ impl ShowSet for Packed<EquationElem> {
         if self.block(styles) {
             out.set(AlignElem::set_alignment(Alignment::CENTER));
             out.set(EquationElem::set_size(MathSize::Display));
+        } else {
+            out.set(EquationElem::set_size(MathSize::Text));
         }
         out.set(TextElem::set_weight(FontWeight::from_number(450)));
         out.set(TextElem::set_font(FontList(vec![FontFamily::new(
diff --git a/tests/ref/bugs/3658-math-size.png b/tests/ref/bugs/3658-math-size.png
new file mode 100644
index 00000000..94c8d388
Binary files /dev/null and b/tests/ref/bugs/3658-math-size.png differ
diff --git a/tests/typ/bugs/3658-math-size.typ b/tests/typ/bugs/3658-math-size.typ
new file mode 100644
index 00000000..63c020b2
--- /dev/null
+++ b/tests/typ/bugs/3658-math-size.typ
@@ -0,0 +1,5 @@
+// https://github.com/typst/typst/issues/3658
+
+---
+$ #rect[$1/2$] $
+$#rect[$1/2$]$