diff --git a/Userland/Libraries/LibWeb/CSS/Display.h b/Userland/Libraries/LibWeb/CSS/Display.h
index dd1f1782a7..634f92d778 100644
--- a/Userland/Libraries/LibWeb/CSS/Display.h
+++ b/Userland/Libraries/LibWeb/CSS/Display.h
@@ -6,6 +6,8 @@
 
 #pragma once
 
+#include <AK/Assertions.h>
+
 namespace Web::CSS {
 
 class Display {
diff --git a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
index 73dffa9310..0a684de2af 100644
--- a/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
+++ b/Userland/Libraries/LibWeb/Layout/FlexFormattingContext.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <LibWeb/Layout/Box.h>
 #include <LibWeb/Layout/FormattingContext.h>
 
 namespace Web::Layout {
diff --git a/Userland/Libraries/LibWeb/Layout/FormattingContext.h b/Userland/Libraries/LibWeb/Layout/FormattingContext.h
index de0208a74e..d88163b4bd 100644
--- a/Userland/Libraries/LibWeb/Layout/FormattingContext.h
+++ b/Userland/Libraries/LibWeb/Layout/FormattingContext.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/OwnPtr.h>
 #include <LibWeb/Forward.h>
 
 namespace Web::Layout {
diff --git a/Userland/Libraries/LibWeb/Layout/TreeBuilder.h b/Userland/Libraries/LibWeb/Layout/TreeBuilder.h
index ae000a4765..7089e4b379 100644
--- a/Userland/Libraries/LibWeb/Layout/TreeBuilder.h
+++ b/Userland/Libraries/LibWeb/Layout/TreeBuilder.h
@@ -8,6 +8,7 @@
 
 #include <AK/NonnullRefPtrVector.h>
 #include <AK/RefPtr.h>
+#include <LibWeb/CSS/Display.h>
 #include <LibWeb/Forward.h>
 
 namespace Web::Layout {