diff --git a/lib/internal/assert/assertion_error.js b/lib/internal/assert/assertion_error.js
index a77414834d1e32..691f057ad281e3 100644
--- a/lib/internal/assert/assertion_error.js
+++ b/lib/internal/assert/assertion_error.js
@@ -13,6 +13,9 @@ const { inspect } = require('internal/util/inspect');
 const { codes: {
   ERR_INVALID_ARG_TYPE
 } } = require('internal/errors');
+const {
+  removeColors,
+} = require('internal/util');
 
 let blue = '';
 let green = '';
@@ -93,7 +96,12 @@ function createErrDiff(actual, expected, operator) {
   // equal, check further special handling.
   if (actualLines.length === 1 && expectedLines.length === 1 &&
     actualLines[0] !== expectedLines[0]) {
-    const inputLength = actualLines[0].length + expectedLines[0].length;
+    // Check for the visible length using the `removeColors()` function, if
+    // appropriate.
+    const c = inspect.defaultOptions.colors;
+    const actualRaw = c ? removeColors(actualLines[0]) : actualLines[0];
+    const expectedRaw = c ? removeColors(expectedLines[0]) : expectedLines[0];
+    const inputLength = actualRaw.length + expectedRaw.length;
     // If the character length of "actual" and "expected" together is less than
     // kMaxShortLength and if neither is an object and at least one of them is
     // not `zero`, use the strict equal comparison to visualize the output.
@@ -110,7 +118,7 @@ function createErrDiff(actual, expected, operator) {
       // not a tty, use a default value of 80 characters.
       const maxLength = process.stderr.isTTY ? process.stderr.columns : 80;
       if (inputLength < maxLength) {
-        while (actualLines[0][i] === expectedLines[0][i]) {
+        while (actualRaw[i] === expectedRaw[i]) {
           i++;
         }
         // Ignore the first characters.
diff --git a/lib/internal/tty.js b/lib/internal/tty.js
index 98975fa68a436f..44d51737008eb0 100644
--- a/lib/internal/tty.js
+++ b/lib/internal/tty.js
@@ -73,18 +73,26 @@ const TERM_ENVS_REG_EXP = [
   /^vt100/
 ];
 
+let warned = false;
 function warnOnDeactivatedColors(env) {
-  let name;
+  if (warned)
+    return;
+  let name = '';
   if (env.NODE_DISABLE_COLORS !== undefined)
     name = 'NODE_DISABLE_COLORS';
-  if (env.NO_COLOR !== undefined)
-    name = 'NO_COLOR';
+  if (env.NO_COLOR !== undefined) {
+    if (name !== '') {
+      name += "' and '";
+    }
+    name += 'NO_COLOR';
+  }
 
-  if (name !== undefined) {
+  if (name !== '') {
     process.emitWarning(
       `The '${name}' env is ignored due to the 'FORCE_COLOR' env being set.`,
       'Warning'
     );
+    warned = true;
   }
 }
 
diff --git a/test/parallel/test-assert.js b/test/parallel/test-assert.js
index 23e1734aff235c..9f45fbb43abdb9 100644
--- a/test/parallel/test-assert.js
+++ b/test/parallel/test-assert.js
@@ -1467,3 +1467,16 @@ assert.throws(
   );
   assert.doesNotMatch('I will pass', /different$/);
 }
+
+{
+  const tempColor = inspect.defaultOptions.colors;
+  assert.throws(() => {
+    inspect.defaultOptions.colors = true;
+    // Guarantee the position indicator is placed correctly.
+    assert.strictEqual(111554n, 11111115);
+  }, (err) => {
+    assert.strictEqual(inspect(err).split('\n')[5], '     ^');
+    inspect.defaultOptions.colors = tempColor;
+    return true;
+  });
+}
diff --git a/test/pseudo-tty/test-assert-colors.js b/test/pseudo-tty/test-assert-colors.js
index a241542c34cebf..9d5a923aa0f8e7 100644
--- a/test/pseudo-tty/test-assert-colors.js
+++ b/test/pseudo-tty/test-assert-colors.js
@@ -2,15 +2,12 @@
 require('../common');
 const assert = require('assert').strict;
 
-try {
-  // Activate colors even if the tty does not support colors.
-  process.env.COLORTERM = '1';
-  // Make sure TERM is not set to e.g., 'dumb' and NODE_DISABLE_COLORS is not
-  // active.
-  process.env.TERM = 'FOOBAR';
+assert.throws(() => {
+  process.env.FORCE_COLOR = '1';
   delete process.env.NODE_DISABLE_COLORS;
+  delete process.env.NO_COLOR;
   assert.deepStrictEqual([1, 2, 2, 2, 2], [2, 2, 2, 2, 2]);
-} catch (err) {
+}, (err) => {
   const expected = 'Expected values to be strictly deep-equal:\n' +
     '\u001b[32m+ actual\u001b[39m \u001b[31m- expected\u001b[39m' +
       ' \u001b[34m...\u001b[39m Lines skipped\n\n' +
@@ -23,4 +20,5 @@ try {
     '    2\n' +
     '  ]';
   assert.strictEqual(err.message, expected);
-}
+  return true;
+});
diff --git a/test/pseudo-tty/test-tty-color-support-warning-2.js b/test/pseudo-tty/test-tty-color-support-warning-2.js
new file mode 100644
index 00000000000000..34ba49c0dfd1b5
--- /dev/null
+++ b/test/pseudo-tty/test-tty-color-support-warning-2.js
@@ -0,0 +1,8 @@
+'use strict';
+
+require('../common');
+
+process.env.NODE_DISABLE_COLORS = '1';
+process.env.FORCE_COLOR = '3';
+
+console.log();
diff --git a/test/pseudo-tty/test-tty-color-support-warning-2.out b/test/pseudo-tty/test-tty-color-support-warning-2.out
new file mode 100644
index 00000000000000..cd57b3f9f69672
--- /dev/null
+++ b/test/pseudo-tty/test-tty-color-support-warning-2.out
@@ -0,0 +1,2 @@
+
+(node:*) Warning: The 'NODE_DISABLE_COLORS' env is ignored due to the 'FORCE_COLOR' env being set.
diff --git a/test/pseudo-tty/test-tty-color-support-warning.js b/test/pseudo-tty/test-tty-color-support-warning.js
new file mode 100644
index 00000000000000..ae164958d2d6b9
--- /dev/null
+++ b/test/pseudo-tty/test-tty-color-support-warning.js
@@ -0,0 +1,9 @@
+'use strict';
+
+require('../common');
+
+process.env.NO_COLOR = '1';
+process.env.NODE_DISABLE_COLORS = '1';
+process.env.FORCE_COLOR = '3';
+
+console.log();
diff --git a/test/pseudo-tty/test-tty-color-support-warning.out b/test/pseudo-tty/test-tty-color-support-warning.out
new file mode 100644
index 00000000000000..9360ae1328b2cd
--- /dev/null
+++ b/test/pseudo-tty/test-tty-color-support-warning.out
@@ -0,0 +1,2 @@
+
+(node:*) Warning: The 'NODE_DISABLE_COLORS' and 'NO_COLOR' env is ignored due to the 'FORCE_COLOR' env being set.
diff --git a/test/pseudo-tty/test-tty-color-support.out b/test/pseudo-tty/test-tty-color-support.out
index f73fbdcd9651f6..e6904d10b8a7b8 100644
--- a/test/pseudo-tty/test-tty-color-support.out
+++ b/test/pseudo-tty/test-tty-color-support.out
@@ -1,8 +1 @@
 (node:*) Warning: The 'NO_COLOR' env is ignored due to the 'FORCE_COLOR' env being set.
-(node:*) Warning: The 'NO_COLOR' env is ignored due to the 'FORCE_COLOR' env being set.
-(node:*) Warning: The 'NO_COLOR' env is ignored due to the 'FORCE_COLOR' env being set.
-(node:*) Warning: The 'NO_COLOR' env is ignored due to the 'FORCE_COLOR' env being set.
-(node:*) Warning: The 'NODE_DISABLE_COLORS' env is ignored due to the 'FORCE_COLOR' env being set.
-(node:*) Warning: The 'NODE_DISABLE_COLORS' env is ignored due to the 'FORCE_COLOR' env being set.
-(node:*) Warning: The 'NODE_DISABLE_COLORS' env is ignored due to the 'FORCE_COLOR' env being set.
-(node:*) Warning: The 'NODE_DISABLE_COLORS' env is ignored due to the 'FORCE_COLOR' env being set.