diff --git a/__tests__/no-deprecated-colors.js b/__tests__/no-deprecated-colors.js
index ecccaf19..1ed6efdf 100644
--- a/__tests__/no-deprecated-colors.js
+++ b/__tests__/no-deprecated-colors.js
@@ -8,15 +8,15 @@ testRule({
   config: [
     true,
     {
-      deprecatedFile: path.join(__dirname, '../plugins/lib/primitives-v8.json'),
-    },
+      deprecatedFile: path.join(__dirname, '../plugins/lib/primitives-v8.json')
+    }
   ],
   fix: true,
   accept: [
     {code: '.x { color: var(--fgColor-default); }'},
     {
-      code: '@include focusOutline(2px, var(--focus-outlineColor));',
-    },
+      code: '@include focusOutline(2px, var(--focus-outlineColor));'
+    }
   ],
   reject: [
     {
@@ -24,49 +24,49 @@ testRule({
       fixed: '.x { color: var(--fgColor-default); }',
       message: `Variable --color-fg-default is deprecated for property color. Please use the replacement --fgColor-default. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border-right: $border-width $border-style var(--color-border-muted); }',
       fixed: '.x { border-right: $border-width $border-style var(--borderColor-muted); }',
       message: `Variable --color-border-muted is deprecated for property border-right. Please use the replacement --borderColor-muted. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border-color: var(--color-primer-border-contrast); }',
       fixed: '.x { border-color: var(--borderColor-muted); }',
       message: `Variable --color-primer-border-contrast is deprecated for property border-color. Please use the replacement --borderColor-muted. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { box-shadow: var(--color-fg-default); }',
       unfixable: true,
       message: `Variable --color-fg-default is deprecated for property box-shadow. Please consult the primer color docs for a replacement. https://primer.style/primitives/storybook/?path=/story/migration-tables (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { background-color: var(--color-canvas-default-transparent); }',
       fixed: '.x { background-color: var(--bgColor-transparent); }',
       message: `Variable --color-canvas-default-transparent is deprecated for property background-color. Please use the replacement --bgColor-transparent. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border: var(--borderWidth-thin) solid var(--color-border-default); }',
       fixed: '.x { border: var(--borderWidth-thin) solid var(--borderColor-default); }',
       message: `Variable --color-border-default is deprecated for property border. Please use the replacement --borderColor-default. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border-color: var(--color-canvas-default-transparent); }',
       fixed: '.x { border-color: var(--borderColor-transparent); }',
       message: `Variable --color-canvas-default-transparent is deprecated for property border-color. Please use the replacement --borderColor-transparent. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border: 1px solid var(--color-neutral-emphasis); .foo { background-color: var(--color-neutral-emphasis); } }',
@@ -76,25 +76,25 @@ testRule({
         true,
         {
           deprecatedFile: path.join(__dirname, '../plugins/lib/primitives-v8.json'),
-          inlineFallback: false,
-        },
+          inlineFallback: false
+        }
       ],
       warnings: [
         {
           message:
             'Variable --color-neutral-emphasis is deprecated for property border. Please use the replacement --borderColor-neutral-emphasis. (primer/no-deprecated-colors)',
           line: 1,
-          column: 6,
+          column: 6
         },
         {
           message:
             'Variable --color-neutral-emphasis is deprecated for property background-color. Please use the replacement --bgColor-neutral-emphasis. (primer/no-deprecated-colors)',
           line: 1,
-          column: 62,
-        },
-      ],
-    },
-  ],
+          column: 62
+        }
+      ]
+    }
+  ]
 })
 // eslint-disable-next-line no-undef
 testRule({
@@ -104,15 +104,15 @@ testRule({
     true,
     {
       deprecatedFile: path.join(__dirname, '../plugins/lib/primitives-v8.json'),
-      inlineFallback: true,
-    },
+      inlineFallback: true
+    }
   ],
   fix: true,
   accept: [
     {code: '.x { color: var(--fgColor-default, var(--color-fg-default)); }'},
     {
-      code: '@include focusOutline(2px, var(--focus-outlineColor, var(--color-accent-fg)));',
-    },
+      code: '@include focusOutline(2px, var(--focus-outlineColor, var(--color-accent-fg)));'
+    }
   ],
   reject: [
     {
@@ -120,42 +120,42 @@ testRule({
       fixed: '.x { color: var(--fgColor-default, var(--color-fg-default)); }',
       message: `Variable --color-fg-default is deprecated for property color. Please use the replacement --fgColor-default. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border-right: $border-width $border-style var(--color-border-muted); }',
       fixed: '.x { border-right: $border-width $border-style var(--borderColor-muted, var(--color-border-muted)); }',
       message: `Variable --color-border-muted is deprecated for property border-right. Please use the replacement --borderColor-muted. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border-color: var(--color-primer-border-contrast); }',
       fixed: '.x { border-color: var(--borderColor-muted, var(--color-primer-border-contrast)); }',
       message: `Variable --color-primer-border-contrast is deprecated for property border-color. Please use the replacement --borderColor-muted. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { background-color: var(--color-canvas-default-transparent); }',
       fixed: '.x { background-color: var(--bgColor-transparent, var(--color-canvas-default-transparent)); }',
       message: `Variable --color-canvas-default-transparent is deprecated for property background-color. Please use the replacement --bgColor-transparent. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border: var(--borderWidth-thin) solid var(--color-border-default); }',
       fixed: '.x { border: var(--borderWidth-thin) solid var(--borderColor-default, var(--color-border-default)); }',
       message: `Variable --color-border-default is deprecated for property border. Please use the replacement --borderColor-default. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border-color: var(--color-canvas-default-transparent); }',
       fixed: '.x { border-color: var(--borderColor-transparent, var(--color-canvas-default-transparent)); }',
       message: `Variable --color-canvas-default-transparent is deprecated for property border-color. Please use the replacement --borderColor-transparent. (primer/no-deprecated-colors)`,
       line: 1,
-      column: 6,
+      column: 6
     },
     {
       code: '.x { border: 1px solid var(--color-neutral-emphasis); .foo { background-color: var(--color-neutral-emphasis); } }',
@@ -165,23 +165,45 @@ testRule({
         true,
         {
           deprecatedFile: path.join(__dirname, '../plugins/lib/primitives-v8.json'),
-          inlineFallback: false,
-        },
+          inlineFallback: false
+        }
       ],
       warnings: [
         {
           message:
             'Variable --color-neutral-emphasis is deprecated for property border. Please use the replacement --borderColor-neutral-emphasis. (primer/no-deprecated-colors)',
           line: 1,
-          column: 6,
+          column: 6
         },
         {
           message:
             'Variable --color-neutral-emphasis is deprecated for property background-color. Please use the replacement --bgColor-neutral-emphasis. (primer/no-deprecated-colors)',
           line: 1,
-          column: 62,
-        },
-      ],
-    },
+          column: 62
+        }
+      ]
+    }
+  ]
+})
+// eslint-disable-next-line no-undef
+testRule({
+  plugins: ['./plugins/no-deprecated-colors.js'],
+  ruleName,
+  config: [
+    true,
+    {
+      deprecatedFile: path.join(__dirname, '../plugins/lib/primitives-v8.json'),
+      inlineFallback: true
+    }
   ],
+  fix: false,
+  accept: [{code: '.x { color: var(--fgColor-default, var(--color-fg-default)); }'}],
+  reject: [
+    {
+      code: '.x { color: var(--fgColor-default); }',
+      message: `Variable --fgColor-default is new color token and must have a fallback value`,
+      line: 1,
+      column: 6
+    }
+  ]
 })
diff --git a/plugins/no-deprecated-colors.js b/plugins/no-deprecated-colors.js
index 6808392f..5ef15af6 100644
--- a/plugins/no-deprecated-colors.js
+++ b/plugins/no-deprecated-colors.js
@@ -9,7 +9,7 @@ const messages = stylelint.utils.ruleMessages(ruleName, {
     }
 
     return `Variable ${varName} is deprecated for property ${property}. Please use the replacement ${replacement}.`
-  },
+  }
 })
 
 // Match CSS variable references (e.g var(--color-text-primary))
@@ -63,6 +63,16 @@ module.exports = stylelint.createPlugin(ruleName, (enabled, options = {}, contex
                 }
               }
             }
+            if (inlineFallback && !replacement.includes(',')) {
+              // report error if inlineFallback is true and replacement does not have a fallback
+              stylelint.utils.report({
+                message: messages.rejected(variableName, replacement, node.prop),
+                node,
+                ruleName,
+                result
+              })
+              continue
+            }
             if (typeof replacement === 'object') {
               replacement = null
             }
@@ -84,7 +94,7 @@ module.exports = stylelint.createPlugin(ruleName, (enabled, options = {}, contex
             message: messages.rejected(variableName, replacement, node.prop),
             node,
             ruleName,
-            result,
+            result
           })
         }
       }
@@ -92,7 +102,7 @@ module.exports = stylelint.createPlugin(ruleName, (enabled, options = {}, contex
   }
 
   log(
-    `${Object.keys(replacedVars).length} deprecated variables replaced with ${Object.keys(newVars).length} variables.`,
+    `${Object.keys(replacedVars).length} deprecated variables replaced with ${Object.keys(newVars).length} variables.`
   )
   return lintResult
 })