diff --git a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
index d0f478eb35..cd37937fda 100644
--- a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
+++ b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.cpp
@@ -633,7 +633,7 @@ void FlexFormattingContext::determine_flex_base_size_and_hypothetical_main_size(
     // The hypothetical main size is the item’s flex base size clamped according to its used min and max main sizes (and flooring the content box size at zero).
     auto clamp_min = has_main_min_size(child_box) ? specified_main_min_size(child_box) : automatic_minimum_size(flex_item);
     auto clamp_max = has_main_max_size(child_box) ? specified_main_max_size(child_box) : NumericLimits<float>::max();
-    flex_item.hypothetical_main_size = css_clamp(flex_item.flex_base_size, clamp_min, clamp_max);
+    flex_item.hypothetical_main_size = max(0, css_clamp(flex_item.flex_base_size, clamp_min, clamp_max));
 }
 
 // https://drafts.csswg.org/css-flexbox-1/#min-size-auto