diff --git a/components/style/driver.rs b/components/style/driver.rs
index c02924b73b3..c6011b6c5a0 100644
--- a/components/style/driver.rs
+++ b/components/style/driver.rs
@@ -49,7 +49,10 @@ fn report_statistics(stats: &PerThreadTraversalStatistics) {
 }
 
 fn parallelism_threshold() -> usize {
-    static_prefs::pref!("layout.css.stylo-parallelism-threshold") as usize
+    #[cfg(feature = "gecko")]
+    return static_prefs::pref!("layout.css.stylo-parallelism-threshold") as usize;
+    #[cfg(feature = "servo")]
+    return 16;
 }
 
 /// Do a DOM traversal for top-down and (optionally) bottom-up processing, generic over `D`.
diff --git a/components/style/parallel.rs b/components/style/parallel.rs
index 815393d050d..d6045ff3802 100644
--- a/components/style/parallel.rs
+++ b/components/style/parallel.rs
@@ -59,7 +59,10 @@ pub const STACK_SAFETY_MARGIN_KB: usize = 168;
 
 /// See documentation of the pref for performance characteristics.
 pub fn work_unit_max() -> usize {
-    static_prefs::pref!("layout.css.stylo-work-unit-size") as usize
+    #[cfg(feature = "gecko")]
+    return static_prefs::pref!("layout.css.stylo-work-unit-size") as usize;
+    #[cfg(feature = "servo")]
+    return 16;
 }
 
 /// A callback to create our thread local context.  This needs to be