diff --git a/__tests__/plugins/letterSpacing.test.js b/__tests__/plugins/letterSpacing.test.js
index 48e08ac2f..af27532fc 100644
--- a/__tests__/plugins/letterSpacing.test.js
+++ b/__tests__/plugins/letterSpacing.test.js
@@ -2,16 +2,14 @@ import _ from 'lodash'
 import escapeClassName from '../../src/util/escapeClassName'
 import plugin from '../../src/plugins/letterSpacing'
 
-test('letter spacing can use default keyword and negative prefix syntax', () => {
+test('letter spacing can use negative prefix syntax', () => {
   const addedUtilities = []
 
   const config = {
     theme: {
       letterSpacing: {
-        '-1': '-0.05em',
-        '-': '-0.025em',
-        default: '0.025em',
-        '1': '0.05em',
+        '-1': '-0.025em',
+        '1': '0.025em',
       },
     },
     variants: {
@@ -44,10 +42,8 @@ test('letter spacing can use default keyword and negative prefix syntax', () =>
   expect(addedUtilities).toEqual([
     {
       utilities: {
-        '.-tracking-1': { 'letter-spacing': '-0.05em' },
-        '.-tracking': { 'letter-spacing': '-0.025em' },
-        '.tracking': { 'letter-spacing': '0.025em' },
-        '.tracking-1': { 'letter-spacing': '0.05em' },
+        '.-tracking-1': { 'letter-spacing': '-0.025em' },
+        '.tracking-1': { 'letter-spacing': '0.025em' },
       },
       variants: ['responsive'],
     },
diff --git a/__tests__/plugins/zIndex.test.js b/__tests__/plugins/zIndex.test.js
index 14dd0e6e1..4493066ed 100644
--- a/__tests__/plugins/zIndex.test.js
+++ b/__tests__/plugins/zIndex.test.js
@@ -2,15 +2,15 @@ import _ from 'lodash'
 import escapeClassName from '../../src/util/escapeClassName'
 import plugin from '../../src/plugins/zIndex'
 
-test('z index can use default keyword and negative prefix syntax', () => {
+test('z index can use negative prefix syntax', () => {
   const addedUtilities = []
 
   const config = {
     theme: {
       zIndex: {
         '-20': '-20',
-        '-': '-10',
-        default: '10',
+        '-10': '-10',
+        '10': '10',
         '20': '20',
       },
     },
@@ -45,8 +45,8 @@ test('z index can use default keyword and negative prefix syntax', () => {
     {
       utilities: {
         '.-z-20': { 'z-index': '-20' },
-        '.-z': { 'z-index': '-10' },
-        '.z': { 'z-index': '10' },
+        '.-z-10': { 'z-index': '-10' },
+        '.z-10': { 'z-index': '10' },
         '.z-20': { 'z-index': '20' },
       },
       variants: ['responsive'],
diff --git a/src/plugins/letterSpacing.js b/src/plugins/letterSpacing.js
index 469416504..bdcd2e5bd 100644
--- a/src/plugins/letterSpacing.js
+++ b/src/plugins/letterSpacing.js
@@ -5,12 +5,8 @@ export default function() {
   return function({ addUtilities, theme, variants, e }) {
     const utilities = _.fromPairs(
       _.map(theme('letterSpacing'), (value, modifier) => {
-        const className =
-          modifier === 'default'
-            ? 'tracking'
-            : `${e(prefixNegativeModifiers('tracking', modifier))}`
         return [
-          `.${className}`,
+          `.${e(prefixNegativeModifiers('tracking', modifier))}`,
           {
             'letter-spacing': value,
           },
diff --git a/src/plugins/zIndex.js b/src/plugins/zIndex.js
index 2b8050f80..479463865 100644
--- a/src/plugins/zIndex.js
+++ b/src/plugins/zIndex.js
@@ -5,10 +5,8 @@ export default function() {
   return function({ addUtilities, e, theme, variants }) {
     const utilities = _.fromPairs(
       _.map(theme('zIndex'), (value, modifier) => {
-        const className =
-          modifier === 'default' ? 'z' : `${e(prefixNegativeModifiers('z', modifier))}`
         return [
-          `.${className}`,
+          `.${e(prefixNegativeModifiers('z', modifier))}`,
           {
             'z-index': value,
           },