diff --git a/src/corePlugins.js b/src/corePlugins.js
index f9a9a97cbabb..1113d0d5ff2f 100644
--- a/src/corePlugins.js
+++ b/src/corePlugins.js
@@ -1014,7 +1014,11 @@ export let divideColor = ({ matchUtilities, theme, corePlugins }) => {
     {
       divide: (value) => {
         if (!corePlugins('divideOpacity')) {
-          return { ['& > :not([hidden]) ~ :not([hidden])']: { 'border-color': value } }
+          return {
+            ['& > :not([hidden]) ~ :not([hidden])']: {
+              'border-color': toColorValue(value),
+            },
+          }
         }
 
         return {
@@ -1174,9 +1178,10 @@ export let borderStyle = ({ addUtilities }) => {
 
 export let borderColor = ({ addBase, matchUtilities, theme, corePlugins }) => {
   if (!corePlugins('borderOpacity')) {
+    let value = theme('borderColor.DEFAULT', 'currentColor')
     addBase({
       '@defaults border-width': {
-        'border-color': theme('borderColor.DEFAULT', 'currentColor'),
+        'border-color': toColorValue(value),
       },
     })
   } else {
@@ -1193,7 +1198,9 @@ export let borderColor = ({ addBase, matchUtilities, theme, corePlugins }) => {
     {
       border: (value) => {
         if (!corePlugins('borderOpacity')) {
-          return { 'border-color': value }
+          return {
+            'border-color': toColorValue(value),
+          }
         }
 
         return withAlphaVariable({
@@ -1213,7 +1220,9 @@ export let borderColor = ({ addBase, matchUtilities, theme, corePlugins }) => {
     {
       'border-t': (value) => {
         if (!corePlugins('borderOpacity')) {
-          return { 'border-top-color': value }
+          return {
+            'border-top-color': toColorValue(value),
+          }
         }
 
         return withAlphaVariable({
@@ -1224,7 +1233,9 @@ export let borderColor = ({ addBase, matchUtilities, theme, corePlugins }) => {
       },
       'border-r': (value) => {
         if (!corePlugins('borderOpacity')) {
-          return { 'border-right-color': value }
+          return {
+            'border-right-color': toColorValue(value),
+          }
         }
 
         return withAlphaVariable({
@@ -1235,7 +1246,9 @@ export let borderColor = ({ addBase, matchUtilities, theme, corePlugins }) => {
       },
       'border-b': (value) => {
         if (!corePlugins('borderOpacity')) {
-          return { 'border-bottom-color': value }
+          return {
+            'border-bottom-color': toColorValue(value),
+          }
         }
 
         return withAlphaVariable({
@@ -1246,7 +1259,9 @@ export let borderColor = ({ addBase, matchUtilities, theme, corePlugins }) => {
       },
       'border-l': (value) => {
         if (!corePlugins('borderOpacity')) {
-          return { 'border-left-color': value }
+          return {
+            'border-left-color': toColorValue(value),
+          }
         }
 
         return withAlphaVariable({
@@ -1272,7 +1287,9 @@ export let backgroundColor = ({ matchUtilities, theme, corePlugins }) => {
     {
       bg: (value) => {
         if (!corePlugins('backgroundOpacity')) {
-          return { 'background-color': value }
+          return {
+            'background-color': toColorValue(value),
+          }
         }
 
         return withAlphaVariable({
@@ -1539,7 +1556,7 @@ export let textColor = ({ matchUtilities, theme, corePlugins }) => {
     {
       text: (value) => {
         if (!corePlugins('textOpacity')) {
-          return { color: value }
+          return { color: toColorValue(value) }
         }
 
         return withAlphaVariable({
@@ -1583,7 +1600,11 @@ export let placeholderColor = ({ matchUtilities, theme, corePlugins }) => {
     {
       placeholder: (value) => {
         if (!corePlugins('placeholderOpacity')) {
-          return { '&::placeholder': { color: value } }
+          return {
+            '&::placeholder': {
+              color: toColorValue(value),
+            },
+          }
         }
 
         return {
diff --git a/tests/opacity.test.css b/tests/opacity.test.css
deleted file mode 100644
index c665bb7b6dfa..000000000000
--- a/tests/opacity.test.css
+++ /dev/null
@@ -1,15 +0,0 @@
-.divide-black > :not([hidden]) ~ :not([hidden]) {
-  border-color: #000;
-}
-.border-black {
-  border-color: #000;
-}
-.bg-black {
-  background-color: #000;
-}
-.text-black {
-  color: #000;
-}
-.placeholder-black::placeholder {
-  color: #000;
-}
diff --git a/tests/opacity.test.html b/tests/opacity.test.html
deleted file mode 100644
index 6942d7713149..000000000000
--- a/tests/opacity.test.html
+++ /dev/null
@@ -1,17 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-  <head>
-    <meta charset="UTF-8" />
-    <link rel="icon" href="/favicon.ico" />
-    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <title>Title</title>
-    <link rel="stylesheet" href="./tailwind.css" />
-  </head>
-  <body>
-    <div class="divide-black"></div>
-    <div class="border-black"></div>
-    <div class="bg-black"></div>
-    <div class="text-black"></div>
-    <div class="placeholder-black"></div>
-  </body>
-</html>
diff --git a/tests/opacity.test.js b/tests/opacity.test.js
index 9fde486bb3e7..24f3f9b2883a 100644
--- a/tests/opacity.test.js
+++ b/tests/opacity.test.js
@@ -1,12 +1,22 @@
 import fs from 'fs'
 import path from 'path'
 
-import { run } from './util/run'
+import { run, html, css } from './util/run'
 
 test('opacity', () => {
   let config = {
     darkMode: 'class',
-    content: [path.resolve(__dirname, './opacity.test.html')],
+    content: [
+      {
+        raw: html`
+          <div class="divide-black"></div>
+          <div class="border-black"></div>
+          <div class="bg-black"></div>
+          <div class="text-black"></div>
+          <div class="placeholder-black"></div>
+        `,
+      },
+    ],
     corePlugins: {
       backgroundOpacity: false,
       borderOpacity: false,
@@ -17,9 +27,74 @@ test('opacity', () => {
   }
 
   return run('@tailwind utilities', config).then((result) => {
-    let expectedPath = path.resolve(__dirname, './opacity.test.css')
-    let expected = fs.readFileSync(expectedPath, 'utf8')
+    expect(result.css).toMatchCss(css`
+      .divide-black > :not([hidden]) ~ :not([hidden]) {
+        border-color: #000;
+      }
+      .border-black {
+        border-color: #000;
+      }
+      .bg-black {
+        background-color: #000;
+      }
+      .text-black {
+        color: #000;
+      }
+      .placeholder-black::placeholder {
+        color: #000;
+      }
+    `)
+  })
+})
 
-    expect(result.css).toMatchCss(expected)
+test('colors defined as functions work when opacity plugins are disabled', () => {
+  let config = {
+    darkMode: 'class',
+    content: [
+      {
+        raw: html`
+          <div class="divide-primary"></div>
+          <div class="border-primary"></div>
+          <div class="bg-primary"></div>
+          <div class="text-primary"></div>
+          <div class="placeholder-primary"></div>
+        `,
+      },
+    ],
+    theme: {
+      colors: {
+        primary: ({ opacityValue }) =>
+          opacityValue === undefined
+            ? 'rgb(var(--color-primary))'
+            : `rgb(var(--color-primary) / ${opacityValue})`,
+      },
+    },
+    corePlugins: {
+      backgroundOpacity: false,
+      borderOpacity: false,
+      divideOpacity: false,
+      placeholderOpacity: false,
+      textOpacity: false,
+    },
+  }
+
+  return run('@tailwind utilities', config).then((result) => {
+    expect(result.css).toMatchCss(css`
+      .divide-primary > :not([hidden]) ~ :not([hidden]) {
+        border-color: rgb(var(--color-primary));
+      }
+      .border-primary {
+        border-color: rgb(var(--color-primary));
+      }
+      .bg-primary {
+        background-color: rgb(var(--color-primary));
+      }
+      .text-primary {
+        color: rgb(var(--color-primary));
+      }
+      .placeholder-primary::placeholder {
+        color: rgb(var(--color-primary));
+      }
+    `)
   })
 })