diff --git a/Kernel/Syscalls/select.cpp b/Kernel/Syscalls/select.cpp
index 0df46b4390..175a07e650 100644
--- a/Kernel/Syscalls/select.cpp
+++ b/Kernel/Syscalls/select.cpp
@@ -48,11 +48,16 @@ KResultOr<int> Process::sys$select(Userspace<const Syscall::SC_select_params*> u
     });
 
     fd_set fds_read, fds_write, fds_except;
-    if (params.readfds && !copy_from_user(&fds_read, params.readfds))
+
+    size_t bytes_used = ceil_div(params.nfds, 8);
+    if (bytes_used > sizeof(fds_read))
+        return EINVAL;
+
+    if (params.readfds && !copy_from_user(&fds_read, params.readfds, bytes_used))
         return EFAULT;
-    if (params.writefds && !copy_from_user(&fds_write, params.writefds))
+    if (params.writefds && !copy_from_user(&fds_write, params.writefds, bytes_used))
         return EFAULT;
-    if (params.exceptfds && !copy_from_user(&fds_except, params.exceptfds))
+    if (params.exceptfds && !copy_from_user(&fds_except, params.exceptfds, bytes_used))
         return EFAULT;
 
     Thread::SelectBlocker::FDVector fds_info;
@@ -111,11 +116,11 @@ KResultOr<int> Process::sys$select(Userspace<const Syscall::SC_select_params*> u
         }
     }
 
-    if (params.readfds && !copy_to_user(params.readfds, &fds_read))
+    if (params.readfds && !copy_to_user(params.readfds, &fds_read, bytes_used))
         return EFAULT;
-    if (params.writefds && !copy_to_user(params.writefds, &fds_write))
+    if (params.writefds && !copy_to_user(params.writefds, &fds_write, bytes_used))
         return EFAULT;
-    if (params.exceptfds && !copy_to_user(params.exceptfds, &fds_except))
+    if (params.exceptfds && !copy_to_user(params.exceptfds, &fds_except, bytes_used))
         return EFAULT;
     return marked_fd_count;
 }