diff --git a/components/style/values/specified/length.rs b/components/style/values/specified/length.rs
index 4a5f213d976..3c7c8a722f1 100644
--- a/components/style/values/specified/length.rs
+++ b/components/style/values/specified/length.rs
@@ -132,11 +132,13 @@ impl FontRelativeLength {
 
         match *self {
             FontRelativeLength::Em(length) => {
-                if matches!(base_size, FontBaseSize::CurrentStyle) {
-                    context.rule_cache_conditions.borrow_mut()
-                        .set_font_size_dependency(
-                            reference_font_size.into()
-                        );
+                if context.for_non_inherited_property.is_some() {
+                    if matches!(base_size, FontBaseSize::CurrentStyle) {
+                        context.rule_cache_conditions.borrow_mut()
+                            .set_font_size_dependency(
+                                reference_font_size.into()
+                            );
+                    }
                 }
                 (reference_font_size, length)
             },