diff --git a/gc.c b/gc.c
index 72328678c5fc1d..e8709dcf281a64 100644
--- a/gc.c
+++ b/gc.c
@@ -1062,7 +1062,7 @@ typed_data_alloc(VALUE klass, VALUE typed_flag, void *datap, const rb_data_type_
     RBIMPL_NONNULL_ARG(type);
     if (klass) rb_data_object_check(klass);
     bool wb_protected = (type->flags & RUBY_FL_WB_PROTECTED) || !type->function.dmark;
-    return newobj_of(GET_RACTOR(), klass, T_DATA, 0, ((VALUE)type) | IS_TYPED_DATA | typed_flag, (VALUE)datap, wb_protected, size);
+    return newobj_of(GET_RACTOR(), klass, T_DATA | RUBY_TYPED_FL_IS_TYPED_DATA, 0, ((VALUE)type) | typed_flag, (VALUE)datap, wb_protected, size);
 }
 
 VALUE
diff --git a/include/ruby/internal/core/rtypeddata.h b/include/ruby/internal/core/rtypeddata.h
index 4d9fd4a6acbde8..8e16c31d998080 100644
--- a/include/ruby/internal/core/rtypeddata.h
+++ b/include/ruby/internal/core/rtypeddata.h
@@ -115,10 +115,8 @@
 #define RUBY_TYPED_PROMOTED1         RUBY_TYPED_PROMOTED1
 /** @endcond */
 
-#define IS_TYPED_DATA ((VALUE)1)
-#define TYPED_DATA_EMBEDDED ((VALUE)2)
-#define TYPED_DATA_PTR_FLAGS ((VALUE)3)
-#define TYPED_DATA_PTR_MASK (~TYPED_DATA_PTR_FLAGS)
+#define TYPED_DATA_EMBEDDED ((VALUE)1)
+#define TYPED_DATA_PTR_MASK (~(TYPED_DATA_EMBEDDED))
 
 /**
  * @private
@@ -181,9 +179,9 @@ rbimpl_typeddata_flags {
     RUBY_TYPED_WB_PROTECTED     = RUBY_FL_WB_PROTECTED, /* THIS FLAG DEPENDS ON Ruby version */
 
     /**
-     * This flag no longer in use
+     * This flag is used to distinguish RTypedData from deprecated RData objects.
      */
-    RUBY_TYPED_UNUSED           = RUBY_FL_UNUSED6,
+    RUBY_TYPED_FL_IS_TYPED_DATA = RUBY_FL_USERPRIV0,
 
     /**
      * This flag determines whether marking and compaction should be carried out
@@ -569,7 +567,7 @@ RBIMPL_ATTR_ARTIFICIAL()
 static inline bool
 rbimpl_rtypeddata_p(VALUE obj)
 {
-    return RTYPEDDATA(obj)->type & IS_TYPED_DATA;
+    return FL_TEST_RAW(obj, RUBY_TYPED_FL_IS_TYPED_DATA);
 }
 
 RBIMPL_ATTR_PURE_UNLESS_DEBUG()
diff --git a/include/ruby/internal/fl_type.h b/include/ruby/internal/fl_type.h
index 9e1f3dd15cf84b..da8670a8086abf 100644
--- a/include/ruby/internal/fl_type.h
+++ b/include/ruby/internal/fl_type.h
@@ -217,11 +217,11 @@ ruby_fl_type {
     RUBY_FL_PROMOTED    = (1<<5),
 
     /**
-     * This flag is no longer in use
+     * This flag meaning is type dependent, currently only used by T_DATA.
      *
      * @internal
      */
-    RUBY_FL_UNUSED6    = (1<<6),
+    RUBY_FL_USERPRIV0    = (1<<6),
 
     /**
      * This flag has  something to do with finalisers.  A  ruby object can have
diff --git a/yjit/src/cruby_bindings.inc.rs b/yjit/src/cruby_bindings.inc.rs
index 429330168b0f29..4d1ce5df5eb746 100644
--- a/yjit/src/cruby_bindings.inc.rs
+++ b/yjit/src/cruby_bindings.inc.rs
@@ -222,7 +222,7 @@ pub const RUBY_FL_USHIFT: ruby_fl_ushift = 12;
 pub type ruby_fl_ushift = u32;
 pub const RUBY_FL_WB_PROTECTED: ruby_fl_type = 32;
 pub const RUBY_FL_PROMOTED: ruby_fl_type = 32;
-pub const RUBY_FL_UNUSED6: ruby_fl_type = 64;
+pub const RUBY_FL_USERPRIV0: ruby_fl_type = 64;
 pub const RUBY_FL_FINALIZE: ruby_fl_type = 128;
 pub const RUBY_FL_TAINT: ruby_fl_type = 0;
 pub const RUBY_FL_EXIVAR: ruby_fl_type = 0;
diff --git a/zjit/src/cruby_bindings.inc.rs b/zjit/src/cruby_bindings.inc.rs
index 0ff09a3c094b0e..0523c00ede24a7 100644
--- a/zjit/src/cruby_bindings.inc.rs
+++ b/zjit/src/cruby_bindings.inc.rs
@@ -103,7 +103,7 @@ pub const RUBY_FL_USHIFT: ruby_fl_ushift = 12;
 pub type ruby_fl_ushift = u32;
 pub const RUBY_FL_WB_PROTECTED: ruby_fl_type = 32;
 pub const RUBY_FL_PROMOTED: ruby_fl_type = 32;
-pub const RUBY_FL_UNUSED6: ruby_fl_type = 64;
+pub const RUBY_FL_USERPRIV0: ruby_fl_type = 64;
 pub const RUBY_FL_FINALIZE: ruby_fl_type = 128;
 pub const RUBY_FL_TAINT: ruby_fl_type = 0;
 pub const RUBY_FL_EXIVAR: ruby_fl_type = 0;