diff --git a/test/dbm/test_dbm.rb b/test/dbm/test_dbm.rb
index c0d3bb42bf..bc48831cdb 100644
--- a/test/dbm/test_dbm.rb
+++ b/test/dbm/test_dbm.rb
@@ -28,7 +28,7 @@ if defined? DBM
     SYSTEM = uname_s
 
     def setup
-      @tmpdir = Dir.tmpdir
+      @tmpdir = Dir.mktmpdir("tmptest_dbm")
       @prefix = "tmptest_dbm_#{$$}"
       @path = "#{@tmpdir}/#{@prefix}_"
       assert_instance_of(DBM, @dbm = DBM.new(@path))
@@ -48,8 +48,7 @@ if defined? DBM
       ObjectSpace.each_object(DBM) do |obj|
         obj.close unless obj.closed?
       end
-      File.delete *Dir.glob("#{@tmpdir}/#{@prefix}*").to_a
-      p Dir.glob("#{@tmpdir}/#{@prefix}*") if $DEBUG
+      FileUtils.remove_entry_secure @tmpdir
     end
 
     def check_size(expect, dbm=@dbm)
diff --git a/test/gdbm/test_gdbm.rb b/test/gdbm/test_gdbm.rb
index 51a8bb3555..928efe9d90 100644
--- a/test/gdbm/test_gdbm.rb
+++ b/test/gdbm/test_gdbm.rb
@@ -28,7 +28,7 @@ if defined? GDBM
     SYSTEM = uname_s
 
     def setup
-      @tmpdir = Dir.tmpdir
+      @tmpdir = Dir.mktmpdir("tmptest_gdbm")
       @prefix = "tmptest_gdbm_#{$$}"
       @path = "#{@tmpdir}/#{@prefix}_"
       assert_instance_of(GDBM, @gdbm = GDBM.new(@path))
@@ -45,8 +45,7 @@ if defined? GDBM
       ObjectSpace.each_object(GDBM) do |obj|
         obj.close unless obj.closed?
       end
-      File.delete *Dir.glob("#{@tmpdir}/#{@prefix}*").to_a
-      p Dir.glob("#{@tmpdir}/#{@prefix}*") if $DEBUG
+      FileUtils.remove_entry_secure @tmpdir
     end
 
     def check_size(expect, gdbm=@gdbm)
diff --git a/test/sdbm/test_sdbm.rb b/test/sdbm/test_sdbm.rb
index 832e41f4fd..0badf7c4b7 100644
--- a/test/sdbm/test_sdbm.rb
+++ b/test/sdbm/test_sdbm.rb
@@ -8,7 +8,7 @@ end
 
 class TestSDBM < Test::Unit::TestCase
   def setup
-    @tmpdir = Dir.tmpdir
+    @tmpdir = Dir.mktmpdir("tmptest_sdbm")
     @prefix = "tmptest_sdbm_#{$$}"
     @path = "#{@tmpdir}/#{@prefix}_"
     assert_instance_of(SDBM, @sdbm = SDBM.new(@path))
@@ -18,8 +18,7 @@ class TestSDBM < Test::Unit::TestCase
     ObjectSpace.each_object(SDBM) do |obj|
       obj.close unless obj.closed?
     end
-    File.delete *Dir.glob("#{@tmpdir}/#{@prefix}*").to_a
-    p Dir.glob("#{@tmpdir}/#{@prefix}*") if $DEBUG
+    FileUtils.remove_entry_secure @tmpdir
   end
 
   def check_size(expect, sdbm=@sdbm)