diff --git a/core/modules/breakpoint/tests/themes/breakpoint_theme_test/breakpoint_theme_test.info.yml b/core/modules/breakpoint/tests/themes/breakpoint_theme_test/breakpoint_theme_test.info.yml
index 779f99764c1d9d82f30cfd17581f13184db0b586..482faf5c634bc4de1b8d2485d56781de90f6afc5 100644
--- a/core/modules/breakpoint/tests/themes/breakpoint_theme_test/breakpoint_theme_test.info.yml
+++ b/core/modules/breakpoint/tests/themes/breakpoint_theme_test/breakpoint_theme_test.info.yml
@@ -3,4 +3,4 @@ type: theme
 description: 'Test theme for breakpoint.'
 version: VERSION
 core: 8.x
-'base theme': bartik
+base theme: bartik
diff --git a/core/modules/system/tests/themes/test_invalid_basetheme/test_invalid_basetheme.info.yml b/core/modules/system/tests/themes/test_invalid_basetheme/test_invalid_basetheme.info.yml
index f29a4d46af79b6c7499ec162bf6c2515ca4fe82f..ab0b49ed0f93c6a75ce222af1458035551c96e94 100644
--- a/core/modules/system/tests/themes/test_invalid_basetheme/test_invalid_basetheme.info.yml
+++ b/core/modules/system/tests/themes/test_invalid_basetheme/test_invalid_basetheme.info.yml
@@ -3,4 +3,4 @@ type: theme
 description: 'Test theme which has a non-existent base theme.'
 version: VERSION
 core: 8.x
-'base theme': not_real_test_basetheme
+base theme: not_real_test_basetheme
diff --git a/core/modules/system/tests/themes/test_subtheme/test_subtheme.info.yml b/core/modules/system/tests/themes/test_subtheme/test_subtheme.info.yml
index 6adfee4b0b31db4da6539dba1c7172574153cf99..cdcd8f0855e74f21a9d0a66083232abd84d207a1 100644
--- a/core/modules/system/tests/themes/test_subtheme/test_subtheme.info.yml
+++ b/core/modules/system/tests/themes/test_subtheme/test_subtheme.info.yml
@@ -3,7 +3,7 @@ type: theme
 description: 'Test theme which uses test_basetheme as the base theme.'
 version: VERSION
 core: 8.x
-'base theme': test_basetheme
+base theme: test_basetheme
 stylesheets:
   all:
     - css/sub-add.css
diff --git a/core/modules/update/tests/themes/update_test_subtheme/update_test_subtheme.info.yml b/core/modules/update/tests/themes/update_test_subtheme/update_test_subtheme.info.yml
index 2580fd6e8ce253902daff2c7bb060363719ba069..0921cc79f8d162a6c5fd4a53958ffb2bb01d1487 100644
--- a/core/modules/update/tests/themes/update_test_subtheme/update_test_subtheme.info.yml
+++ b/core/modules/update/tests/themes/update_test_subtheme/update_test_subtheme.info.yml
@@ -3,4 +3,4 @@ type: theme
 description: 'Test theme which uses update_test_basetheme as the base theme.'
 version: VERSION
 core: 8.x
-'base theme': update_test_basetheme
+base theme: update_test_basetheme