diff --git a/Userland/Libraries/LibCore/System.h b/Userland/Libraries/LibCore/System.h
index 5cf3487825..ea00998ac7 100644
--- a/Userland/Libraries/LibCore/System.h
+++ b/Userland/Libraries/LibCore/System.h
@@ -35,6 +35,10 @@
 #    include <shadow.h>
 #endif
 
+#ifdef AK_OS_SOLARIS
+#    include <sys/filio.h>
+#endif
+
 namespace Core::System {
 
 #ifdef AK_OS_SERENITY