diff --git a/Kernel/FileSystem/InodeFile.cpp b/Kernel/FileSystem/InodeFile.cpp
index ad252f1d24..7c5c93c728 100644
--- a/Kernel/FileSystem/InodeFile.cpp
+++ b/Kernel/FileSystem/InodeFile.cpp
@@ -83,6 +83,11 @@ ErrorOr<void> InodeFile::ioctl(OpenFileDescription& description, unsigned reques
 
 ErrorOr<Memory::Region*> InodeFile::mmap(Process& process, OpenFileDescription& description, Memory::VirtualRange const& range, u64 offset, int prot, bool shared)
 {
+    // FIXME: Support writing changes made to shared file mappings back to disk.
+    // Some ports behave incorrectly if we silently discard writes to memory-mapped files, so let's not lie about what we can do.
+    if (shared && (prot & PROT_WRITE))
+        return ENOTSUP;
+
     // FIXME: If PROT_EXEC, check that the underlying file system isn't mounted noexec.
     RefPtr<Memory::InodeVMObject> vmobject;
     if (shared)