diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index 3e9f4d1bc2..c0631b55f1 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -1086,6 +1086,28 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
     end;
   end
 
+  def test_blocking_backtrace
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      class Bug < RuntimeError
+        def backtrace
+          IO.readlines(IO::NULL)
+        end
+      end
+      bug = Bug.new '[ruby-core:85939] [Bug #14577]'
+      n = 10000
+      i = 0
+      n.times do
+        begin
+          raise bug
+        rescue Bug
+          i += 1
+        end
+      end
+      assert_equal(n, i)
+    end;
+  end
+
   def test_wrong_backtrace
     assert_separately([], "#{<<-"begin;"}\n#{<<-"end;"}")
     begin;
diff --git a/thread.c b/thread.c
index fad0ce6efc..d7e0d91d7f 100644
--- a/thread.c
+++ b/thread.c
@@ -392,7 +392,7 @@ unblock_function_set(rb_thread_t *th, rb_unblock_function_t *func, void *arg, in
 	}
 
 	native_mutex_lock(&th->interrupt_lock);
-    } while (RUBY_VM_INTERRUPTED_ANY(th->ec) &&
+    } while (!th->ec->raised_flag && RUBY_VM_INTERRUPTED_ANY(th->ec) &&
 	     (native_mutex_unlock(&th->interrupt_lock), TRUE));
 
     VM_ASSERT(th->unblock.func == NULL);
diff --git a/version.h b/version.h
index 5f61820826..3b51c13bce 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.5.0"
 #define RUBY_RELEASE_DATE "2018-03-20"
-#define RUBY_PATCHLEVEL 43
+#define RUBY_PATCHLEVEL 44
 
 #define RUBY_RELEASE_YEAR 2018
 #define RUBY_RELEASE_MONTH 3