diff --git a/lib/rb-inotify/native/flags.rb b/lib/rb-inotify/native/flags.rb
index 5640130..bc59607 100644
--- a/lib/rb-inotify/native/flags.rb
+++ b/lib/rb-inotify/native/flags.rb
@@ -11,31 +11,31 @@ module Flags
       IN_ATTRIB = 0x00000004
       # Writtable file was closed.
       IN_CLOSE_WRITE = 0x00000008
-      # File was modified.
-      IN_MODIFY = 0x00000002
       # Unwrittable file closed.
       IN_CLOSE_NOWRITE = 0x00000010
-      # File was opened.
-      IN_OPEN = 0x00000020
-      # File was moved from X.
-      IN_MOVED_FROM = 0x00000040
-      # File was moved to Y.
-      IN_MOVED_TO = 0x00000080
       # Subfile was created.
       IN_CREATE = 0x00000100
       # Subfile was deleted.
       IN_DELETE = 0x00000200
       # Self was deleted.
       IN_DELETE_SELF = 0x00000400
+      # File was modified.
+      IN_MODIFY = 0x00000002
       # Self was moved.
       IN_MOVE_SELF = 0x00000800
+      # File was moved from X.
+      IN_MOVED_FROM = 0x00000040
+      # File was moved to Y.
+      IN_MOVED_TO = 0x00000080
+      # File was opened.
+      IN_OPEN = 0x00000020
 
       ## Helper events.
 
-      # Close.
-      IN_CLOSE = (IN_CLOSE_WRITE | IN_CLOSE_NOWRITE)
       # Moves.
       IN_MOVE = (IN_MOVED_FROM | IN_MOVED_TO)
+      # Close.
+      IN_CLOSE = (IN_CLOSE_WRITE | IN_CLOSE_NOWRITE)
       # All events which a program can wait on.
       IN_ALL_EVENTS = (IN_ACCESS | IN_MODIFY | IN_ATTRIB | IN_CLOSE_WRITE |
         IN_CLOSE_NOWRITE | IN_OPEN | IN_MOVED_FROM | IN_MOVED_TO | IN_CREATE |
@@ -44,26 +44,35 @@ module Flags
 
       ## Special flags.
 
-      # Only watch the path if it is a directory.
-      IN_ONLYDIR = 0x01000000
-      # Do not follow a sym link.
+      # Do not follow a sym link
+      # available since Linux 2.6.15, causes EINVAL othervise
       IN_DONT_FOLLOW = 0x02000000
+      # Exclude events on unlinked objects.
+      # available since Linux 2.6.36, causes EINVAL othervise
+      IN_EXCL_UNLINK = 0x04000000
       # Add to the mask of an already existing watch.
       IN_MASK_ADD = 0x20000000
       # Only send event once.
       IN_ONESHOT = 0x80000000
-
+      # Only watch the path if it is a directory.
+      # available since Linux 2.6.15, causes EINVAL othervise
+      IN_ONLYDIR = 0x01000000
+      # Only create watches.
+      # available since Linux 4.18, causes EINVAL othervise
+      IN_MASK_CREATE = 0x10000000
 
       ## Events sent by the kernel.
 
-      # Backing fs was unmounted.
-      IN_UNMOUNT = 0x00002000
-      # Event queued overflowed.
-      IN_Q_OVERFLOW = 0x00004000
       # File was ignored.
       IN_IGNORED = 0x00008000
       # Event occurred against dir.
       IN_ISDIR = 0x40000000
+      # Event queued overflowed.
+      IN_Q_OVERFLOW = 0x00004000
+      # Backing fs was unmounted.
+      IN_UNMOUNT = 0x00002000
+
+      EVENT_ONLY_FLAGS = IN_IGNORED | IN_ISDIR | IN_UNMOUNT | IN_Q_OVERFLOW
 
       ## fpathconf Macros
 
@@ -75,10 +84,23 @@ module Flags
       # @param flags [Array<Symbol>]
       # @return [Fixnum]
       def self.to_mask(flags)
-        flags.map {|flag| const_get("IN_#{flag.to_s.upcase}")}.
+        flags.map {|flag| to_add_watch_flag(flag) }.
           inject(0) {|mask, flag| mask | flag}
       end
 
+      # Converts a flag to the value that can be used in inotify_add_watch
+      #
+      # @param flag [Symbol]
+      # @return [Fixnum]
+      # @raise [NameError] if the flag is not supported
+      # @raise [ArgumentError] if the flag is defined, but can't be used in inotify_add_watch
+      def self.to_add_watch_flag(flag)
+        res = const_get("IN_#{flag.to_s.upcase}")
+        raise ArgumentError, "Invalid flag: #{flag}" if EVENT_ONLY_FLAGS & res != 0
+
+        res
+      end
+
       # Converts a bitmask from the C API into a list of flags.
       #
       # @param mask [Fixnum]
diff --git a/lib/rb-inotify/notifier.rb b/lib/rb-inotify/notifier.rb
index 398ef99..5c8ecb4 100644
--- a/lib/rb-inotify/notifier.rb
+++ b/lib/rb-inotify/notifier.rb
@@ -164,10 +164,16 @@ def to_io
     # Instead, they specify options for the watcher.
     #
     # `:onlydir`
-    # : Only watch the path if it's a directory.
+    # : Only watch the path if it's a directory; since Linux 2.6.15.
     #
     # `:dont_follow`
-    # : Don't follow symlinks.
+    # : Don't follow symlinks; since Linux 2.6.15.
+    #
+    # `:excl_unlink`
+    # : Exclude events on unlinked objects; since Linux 2.6.36.
+    #
+    # `:mask_create`
+    # : Watch pathname only if it does not already have a watch associated with it, Errno::EEXIST is raised otherwise; since Linux 4.18.
     #
     # `:mask_add`
     # : Add these flags to the pre-existing flags for this path.
diff --git a/spec/notifier_spec.rb b/spec/notifier_spec.rb
index 8370151..41b1bad 100644
--- a/spec/notifier_spec.rb
+++ b/spec/notifier_spec.rb
@@ -41,6 +41,26 @@
         expect(events.first.absolute_name).to eq(dir.join("test.txt").to_s)
       end
 
+      it "ensures that new watches do not modify existing ones" do
+        recording(dir, :create, :oneshot, :mask_create)
+        expect do
+          recording(dir, :create, :oneshot, :mask_create)
+        end.to raise_error(Errno::EEXIST)
+        dir.join("test.txt").write("hello world")
+        expect do
+          recording(dir, :create, :oneshot, :mask_create)
+        end.not_to raise_error
+      end
+
+      it "fails if flags are not supported" do
+        expect do
+          recording(dir, :create, :oneshot, :unknown_flag)
+        end.to raise_error(NameError, 'uninitialized constant INotify::Native::Flags::IN_UNKNOWN_FLAG')
+        expect do
+          recording(dir, :create, :isdir)
+        end.to raise_error(ArgumentError, 'Invalid flag: isdir')
+      end
+
       it "gets simultaneous events" do
         events = recording(dir, :create)