diff --git a/testsuite/tests/ghci/should_run/all.T b/testsuite/tests/ghci/should_run/all.T
index a9e280ad069d8727c1384ffbb659ea69c2f110cd..4a629350a2ec3b83235d196695ef17dedf607586 100644
--- a/testsuite/tests/ghci/should_run/all.T
+++ b/testsuite/tests/ghci/should_run/all.T
@@ -46,7 +46,7 @@ test('T15369',     just_ghci, ghci_script, ['T15369.script'])
 
 test('T15633a',
      [extra_files(['tc-plugin-ghci/']),
-      when(opsys('mingw32'), multi_cpu_race),
+      when(opsys('mingw32'), [multi_cpu_race, fragile(16813)]),
       only_ways(['ghci']),
       pre_cmd('$MAKE -s --no-print-directory -C tc-plugin-ghci package.plugins01 TOP={top}'),
       extra_hc_opts("-package-db tc-plugin-ghci/pkg.plugins01/local.package.conf -fplugin TcPluginGHCi")
@@ -55,7 +55,7 @@ test('T15633a',
 
 test('T15633b',
      [extra_files(['tc-plugin-ghci/']),
-      when(opsys('mingw32'), multi_cpu_race),
+      when(opsys('mingw32'), [multi_cpu_race, fragile(16813)]),
       only_ways(['ghci']),
       pre_cmd('$MAKE -s --no-print-directory -C tc-plugin-ghci package.plugins01 TOP={top}'),
       extra_hc_opts("-package-db tc-plugin-ghci/pkg.plugins01/local.package.conf")