diff --git a/gtk/theme/HighContrast/_common.scss b/gtk/theme/HighContrast/_common.scss
index ccdb6f6d1e..567a7d5fde 100644
--- a/gtk/theme/HighContrast/_common.scss
+++ b/gtk/theme/HighContrast/_common.scss
@@ -1635,7 +1635,7 @@ GtkCheckButton.text-button, GtkRadioButton.text-button {
       color: $insensitive_fg_color;
       &:backdrop { color: $insensitive_fg_color; }
     }
-    &:inconsistent {
+    &:indeterminate {
       -gtk-icon-source: -gtk-icontheme('#{$a}-mixed-symbolic');
     }
     &:backdrop {
@@ -2063,7 +2063,7 @@ calendar {
     }
   }
 
-  &:inconsistent, &:inconsistent:backdrop { color: gtkalpha(currentColor, 0.55); }
+  &:indeterminate, &:indeterminate:backdrop { color: gtkalpha(currentColor, 0.55); }
   &.highlight, &.highlight:backdrop { color: $fg_color; }
 }
 
@@ -2564,10 +2564,10 @@ cursor-handle {
                   (':hover', '-unchecked-hover'),
                   (':active', '-unchecked-active'),
                   (':disabled','-unchecked-insensitive'),
-                  (':inconsistent', '-mixed'),
-                  (':inconsistent:hover', '-mixed-hover'),
-                  (':inconsistent:selected', '-mixed-active'),
-                  (':inconsistent:disabled', '-mixed-insensitive'),
+                  (':indeterminate', '-mixed'),
+                  (':indeterminate:hover', '-mixed-hover'),
+                  (':indeterminate:selected', '-mixed-active'),
+                  (':indeterminate:disabled', '-mixed-insensitive'),
                   (':checked', '-checked'),
                   (':checked:disabled','-checked-insensitive'),
                   (':checked:hover', '-checked-hover'),
diff --git a/gtk/theme/HighContrast/gtk.css b/gtk/theme/HighContrast/gtk.css
index 5e878c98f8..e8e5536265 100644
--- a/gtk/theme/HighContrast/gtk.css
+++ b/gtk/theme/HighContrast/gtk.css
@@ -1757,7 +1757,7 @@ GtkCheckButton.text-button, GtkRadioButton.text-button {
     color: gray; }
     .check:disabled:backdrop {
       color: gray; }
-  .check:inconsistent {
+  .check:indeterminate {
     -gtk-icon-source: -gtk-icontheme("checkbox-mixed-symbolic"); }
   .check:backdrop {
     color: #000; }
@@ -1782,7 +1782,7 @@ GtkCheckButton.text-button, GtkRadioButton.text-button {
     color: gray; }
     .radio:disabled:backdrop {
       color: gray; }
-  .radio:inconsistent {
+  .radio:indeterminate {
     -gtk-icon-source: -gtk-icontheme("radio-mixed-symbolic"); }
   .radio:backdrop {
     color: #000; }
@@ -2292,7 +2292,7 @@ calendar {
     calendar.header:backdrop {
       background-image: linear-gradient(to bottom, #fff);
       border-bottom-color: #c6c6c6; }
-  calendar:inconsistent, calendar:inconsistent:backdrop {
+  calendar:indeterminate, calendar:indeterminate:backdrop {
     color: alpha(currentColor,0.55); }
   calendar.highlight, calendar.highlight:backdrop {
     color: #000; }
@@ -2884,16 +2884,16 @@ cursor-handle {
   .touch-selection .check:disabled {
     -gtk-icon-shadow: none;
     color: #fff; }
-  .touch-selection .check:inconsistent {
+  .touch-selection .check:indeterminate {
     -gtk-icon-shadow: none;
     color: #fff; }
-  .touch-selection .check:inconsistent:hover {
+  .touch-selection .check:indeterminate:hover {
     -gtk-icon-shadow: none;
     color: #fff; }
-  .touch-selection .check:inconsistent:selected {
+  .touch-selection .check:indeterminate:selected {
     -gtk-icon-shadow: none;
     color: #fff; }
-  .touch-selection .check:inconsistent:disabled {
+  .touch-selection .check:indeterminate:disabled {
     -gtk-icon-shadow: none;
     color: #fff; }
   .touch-selection .check:checked {
@@ -2923,16 +2923,16 @@ cursor-handle {
   .touch-selection .radio:disabled {
     -gtk-icon-shadow: none;
     color: #fff; }
-  .touch-selection .radio:inconsistent {
+  .touch-selection .radio:indeterminate {
     -gtk-icon-shadow: none;
     color: #fff; }
-  .touch-selection .radio:inconsistent:hover {
+  .touch-selection .radio:indeterminate:hover {
     -gtk-icon-shadow: none;
     color: #fff; }
-  .touch-selection .radio:inconsistent:selected {
+  .touch-selection .radio:indeterminate:selected {
     -gtk-icon-shadow: none;
     color: #fff; }
-  .touch-selection .radio:inconsistent:disabled {
+  .touch-selection .radio:indeterminate:disabled {
     -gtk-icon-shadow: none;
     color: #fff; }
   .touch-selection .radio:checked {