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 779f997..482faf5 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 f29a4d4..ab0b49e 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 6adfee4..cdcd8f0 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 2580fd6..0921cc7 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