diff --git a/concurrent_set.c b/concurrent_set.c
index 42ff6ef43f799e..cdc7879f4cd307 100644
--- a/concurrent_set.c
+++ b/concurrent_set.c
@@ -2,6 +2,7 @@
 #include "internal/gc.h"
 #include "internal/concurrent_set.h"
 #include "ruby/atomic.h"
+#include "ruby/ractor.h"
 #include "vm_sync.h"
 
 #define CONCURRENT_SET_CONTINUATION_BIT ((VALUE)1 << (sizeof(VALUE) * CHAR_BIT - 1))
@@ -102,6 +103,9 @@ rb_concurrent_set_new(const struct rb_concurrent_set_funcs *funcs, int capacity)
     set->funcs = funcs;
     set->entries = ZALLOC_N(struct concurrent_set_entry, capacity);
     set->capacity = capacity;
+    /* The set is reachable from every Ractor (e.g. via C globals such as the
+     * frozen-string and symbol tables), so mark it shareable. */
+    RB_OBJ_SET_SHAREABLE(obj);
     return obj;
 }
 
diff --git a/depend b/depend
index 22ae43b21ad589..8b764bd060c49c 100644
--- a/depend
+++ b/depend
@@ -2353,6 +2353,7 @@ concurrent_set.$(OBJEXT): {$(VPATH)}missing.h
 concurrent_set.$(OBJEXT): {$(VPATH)}node.h
 concurrent_set.$(OBJEXT): {$(VPATH)}onigmo.h
 concurrent_set.$(OBJEXT): {$(VPATH)}oniguruma.h
+concurrent_set.$(OBJEXT): {$(VPATH)}ractor.h
 concurrent_set.$(OBJEXT): {$(VPATH)}ruby_assert.h
 concurrent_set.$(OBJEXT): {$(VPATH)}ruby_atomic.h
 concurrent_set.$(OBJEXT): {$(VPATH)}rubyparser.h
diff --git a/id_table.c b/id_table.c
index f45cd2c61e1199..a1cc9043b6cff2 100644
--- a/id_table.c
+++ b/id_table.c
@@ -390,6 +390,10 @@ rb_managed_id_table_dup(VALUE old_table)
 {
     struct rb_id_table *new_tbl;
     VALUE obj = TypedData_Make_Struct(0, struct rb_id_table, RTYPEDDATA_TYPE(old_table), new_tbl);
+    /* A managed id table hangs off VM-global state (e.g. a shape tree's edge
+     * table grows via this dup) and is reachable from every Ractor, so mark it
+     * shareable. */
+    RB_OBJ_SET_SHAREABLE(obj);
     struct rb_id_table *old_tbl = managed_id_table_ptr(old_table);
     rb_id_table_init(new_tbl, old_tbl->num + 1);
     rb_id_table_foreach(old_tbl, managed_id_table_dup_i, new_tbl);
diff --git a/symbol.c b/symbol.c
index b157d2677cdae3..513e7ce33774c0 100644
--- a/symbol.c
+++ b/symbol.c
@@ -278,6 +278,9 @@ set_id_entry(rb_symbols_t *symbols, rb_id_serial_t num, VALUE str, VALUE sym)
     if (idx >= (size_t)RARRAY_LEN(ids) || NIL_P(id_entry_list = rb_ary_entry(ids, (long)idx))) {
         rb_darray_make(&entries, ID_ENTRY_UNIT);
         id_entry_list = TypedData_Wrap_Struct(0, &sym_id_entry_list_type, entries);
+        /* Reachable from every Ractor via the global symbol table, so mark it
+         * shareable. */
+        RB_OBJ_SET_SHAREABLE(id_entry_list);
         rb_ary_store(ids, (long)idx, id_entry_list);
     }
     else {
diff --git a/test/ruby/test_ractor.rb b/test/ruby/test_ractor.rb
index e7eb0cd4b34fe7..65c4756dc0bc02 100644
--- a/test/ruby/test_ractor.rb
+++ b/test/ruby/test_ractor.rb
@@ -372,6 +372,13 @@ def test_ractor_new_raises_isolation_error_if_proc_uses_yield
     end
   end
 
+  def test_ractor_does_not_inherit_fiber_storage
+    assert_ractor(<<~'RUBY')
+      Fiber[:key] = "creator"
+      assert_nil Ractor.new { Fiber[:key] }.value
+    RUBY
+  end
+
   def assert_make_shareable(obj)
     refute Ractor.shareable?(obj), "object was already shareable"
     Ractor.make_shareable(obj)
diff --git a/vm_trace.c b/vm_trace.c
index 8ef805dc1fe9d4..542b1869e08a84 100644
--- a/vm_trace.c
+++ b/vm_trace.c
@@ -1950,8 +1950,10 @@ rb_postponed_job_flush(rb_vm_t *vm)
             while (triggered_bits) {
                 unsigned int i = bit_length(triggered_bits) - 1;
                 triggered_bits ^= ((1UL) << i); /* toggle ith bit off */
-                rb_postponed_job_func_t func = pjq->table[i].func;
-                void *data = pjq->table[i].data;
+                /* Read atomically to pair with the atomic CAS/EXCHANGE stores in
+                 * rb_postponed_job_preregister, which can run on another thread. */
+                rb_postponed_job_func_t func = (rb_postponed_job_func_t)(uintptr_t)RUBY_ATOMIC_PTR_LOAD(pjq->table[i].func);
+                void *data = RUBY_ATOMIC_PTR_LOAD(pjq->table[i].data);
                 (func)(data);
             }