diff --git a/packages/components/dark.full.css b/packages/components/dark.full.css
index 78c7a48b7..37f66b9ce 100644
--- a/packages/components/dark.full.css
+++ b/packages/components/dark.full.css
@@ -794,7 +794,7 @@
   --ix-select-option-padding: 8px 12px;
   --ix-select-option-label-margin-left: 8px;
   --ix-select-option-container-padding: 4px 0;
-  --ix-select-option-group-margin: 0 12;
+  --ix-select-option-group-margin: 0 12px;
   --ix-select-option-group-padding-left: 0;
   --ix-select-multiple-option-grouped-padding-left: 12px;
   --ix-select-option-grouped-padding-left: 24px;
diff --git a/packages/components/default.full.css b/packages/components/default.full.css
index 948a906e5..bf093ffe4 100644
--- a/packages/components/default.full.css
+++ b/packages/components/default.full.css
@@ -794,7 +794,7 @@
   --ix-select-option-padding: 8px 12px;
   --ix-select-option-label-margin-left: 8px;
   --ix-select-option-container-padding: 4px 0;
-  --ix-select-option-group-margin: 0 12;
+  --ix-select-option-group-margin: 0 12px;
   --ix-select-option-group-padding-left: 0;
   --ix-select-multiple-option-grouped-padding-left: 12px;
   --ix-select-option-grouped-padding-left: 24px;
diff --git a/packages/components/select/docs/Theme.zh.md b/packages/components/select/docs/Theme.zh.md
index 565d733f2..dc32a019a 100644
--- a/packages/components/select/docs/Theme.zh.md
+++ b/packages/components/select/docs/Theme.zh.md
@@ -3,7 +3,7 @@
 | `multipleOptionGroupedPaddingLeft` |  | `number` | `12` | `12` |
 | `optionContainerPadding` |  | `string | number` | `4px 0` | `4px 0` |
 | `optionFontSize` |  | `number` | `12` | `12` |
-| `optionGroupMargin` |  | `string | number` | `0 12` | `0 12` |
+| `optionGroupMargin` |  | `string | number` | `0 12px` | `0 12px` |
 | `optionGroupPaddingLeft` |  | `number` | `0` | `0` |
 | `optionGroupedPaddingLeft` |  | `number` | `24` | `24` |
 | `optionHeight` |  | `number` | `32` | `32` |
diff --git a/packages/components/select/theme/dark.css b/packages/components/select/theme/dark.css
index 52f58a868..3e5e409ad 100644
--- a/packages/components/select/theme/dark.css
+++ b/packages/components/select/theme/dark.css
@@ -5,7 +5,7 @@
   --ix-select-option-padding: 8px 12px;
   --ix-select-option-label-margin-left: 8px;
   --ix-select-option-container-padding: 4px 0;
-  --ix-select-option-group-margin: 0 12;
+  --ix-select-option-group-margin: 0 12px;
   --ix-select-option-group-padding-left: 0;
   --ix-select-multiple-option-grouped-padding-left: 12px;
   --ix-select-option-grouped-padding-left: 24px;
diff --git a/packages/components/select/theme/default.css b/packages/components/select/theme/default.css
index 52f58a868..3e5e409ad 100644
--- a/packages/components/select/theme/default.css
+++ b/packages/components/select/theme/default.css
@@ -5,7 +5,7 @@
   --ix-select-option-padding: 8px 12px;
   --ix-select-option-label-margin-left: 8px;
   --ix-select-option-container-padding: 4px 0;
-  --ix-select-option-group-margin: 0 12;
+  --ix-select-option-group-margin: 0 12px;
   --ix-select-option-group-padding-left: 0;
   --ix-select-multiple-option-grouped-padding-left: 12px;
   --ix-select-option-grouped-padding-left: 24px;
diff --git a/packages/components/select/theme/default.ts b/packages/components/select/theme/default.ts
index 3153a36df..d59aca3c9 100644
--- a/packages/components/select/theme/default.ts
+++ b/packages/components/select/theme/default.ts
@@ -25,7 +25,7 @@ export function getDefaultThemeTokens(tokens: GlobalThemeTokens): CertainThemeTo
 
     optionLabelMarginLeft: marginSizeSm,
     optionContainerPadding: `${paddingSizeXs}px 0`,
-    optionGroupMargin: `0 ${marginSizeMd}`,
+    optionGroupMargin: `0 ${marginSizeMd}px`,
     optionGroupPaddingLeft: 0,
     multipleOptionGroupedPaddingLeft: paddingSizeMd,
     optionGroupedPaddingLeft: paddingSizeXl,