diff --git a/package-lock.json b/package-lock.json
index 997d964ea..062807fac 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "styled-system",
-  "version": "4.1.1",
+  "version": "4.2.0-0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index eb86bdf94..bb75bdfa7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "styled-system",
-  "version": "4.1.1",
+  "version": "4.2.0-0",
   "description": "Responsive, theme-based style props for building design systems with React",
   "main": "dist/index.cjs.js",
   "module": "dist/index.esm.js",
@@ -58,6 +58,11 @@
       "bench",
       "examples",
       "packages/**/*"
+    ],
+    "reporter": [
+      "lcov",
+      "text-summary",
+      "html"
     ]
   },
   "bundlesize": [
diff --git a/src/index.js b/src/index.js
index c5435234f..34bd955ca 100644
--- a/src/index.js
+++ b/src/index.js
@@ -35,6 +35,30 @@ export const createMediaQuery = n => `@media screen and (min-width: ${px(n)})`
 
 const getValue = (n, scale) => get(scale, n)
 
+// loosely based on deepmerge package
+export const merge = (a, b) => {
+  const result = {}
+  for (const key in a) {
+    result[key] = a[key]
+  }
+  for (const key in b) {
+    if (!a[key]) {
+      result[key] = b[key]
+    } else {
+      result[key] = merge(a[key], b[key])
+    }
+  }
+  return result
+}
+
+const mergeAll = (...args) => {
+  let result = {}
+  for (let i = 0; i < args.length; i++) {
+    result = merge(result, args[i])
+  }
+  return result
+}
+
 export const style = ({
   prop,
   cssProperty,
@@ -83,7 +107,7 @@ export const style = ({
       styles.sort()
     }
 
-    return styles
+    return mergeAll(...styles)
   }
 
   func.propTypes = {
@@ -108,7 +132,7 @@ export const style = ({
 export const compose = (...funcs) => {
   const func = props => {
     const n = funcs.map(fn => fn(props)).filter(Boolean)
-    return n
+    return mergeAll(...n)
   }
 
   func.propTypes = {}
diff --git a/test/index.js b/test/index.js
index b5b6d5cdf..4960c87ae 100644
--- a/test/index.js
+++ b/test/index.js
@@ -10,6 +10,7 @@ import {
   variant,
   cloneFunction,
   mapProps,
+  merge,
 } from '../src'
 
 const width = style({
@@ -88,32 +89,32 @@ test('returns an array of responsive style objects', t => {
   const style = width({
     width: ['100%', '50%'],
   })
-  t.deepEqual(style, [
-    { width: '100%' },
-    { '@media screen and (min-width: 40em)': { width: '50%' } },
-  ])
+  t.deepEqual(style, {
+    width: '100%',
+    '@media screen and (min-width: 40em)': { width: '50%' },
+  })
 })
 
 test('returns an array of responsive style objects for all breakpoints', t => {
   const style = width({
     width: ['100%', '75%', '50%', '33%', '25%'],
   })
-  t.deepEqual(style, [
-    { width: '100%' },
-    { '@media screen and (min-width: 40em)': { width: '75%' } },
-    { '@media screen and (min-width: 52em)': { width: '50%' } },
-    { '@media screen and (min-width: 64em)': { width: '33%' } },
-  ])
+  t.deepEqual(style, {
+    width: '100%',
+    '@media screen and (min-width: 40em)': { width: '75%' },
+    '@media screen and (min-width: 52em)': { width: '50%' },
+    '@media screen and (min-width: 64em)': { width: '33%' },
+  })
 })
 
 test('skips undefined responsive values', t => {
   const style = width({
     width: ['100%', , '50%'],
   })
-  t.deepEqual(style, [
-    { width: '100%' },
-    { '@media screen and (min-width: 52em)': { width: '50%' } },
-  ])
+  t.deepEqual(style, {
+    width: '100%',
+    '@media screen and (min-width: 52em)': { width: '50%' },
+  })
 })
 
 test('parses object values', t => {
@@ -123,10 +124,10 @@ test('parses object values', t => {
       2: '50%',
     },
   })
-  t.deepEqual(style, [
-    { width: '100%' },
-    { '@media screen and (min-width: 64em)': { width: '50%' } },
-  ])
+  t.deepEqual(style, {
+    width: '100%',
+    '@media screen and (min-width: 64em)': { width: '50%' },
+  })
 })
 
 test('get returns a value', t => {
@@ -191,7 +192,7 @@ test('compose combines style functions', t => {
     bg: 'black',
   })
   t.is(typeof colors, 'function')
-  t.deepEqual(styles, [{ color: 'tomato' }, { backgroundColor: 'black' }])
+  t.deepEqual(styles, { color: 'tomato', backgroundColor: 'black' })
 })
 
 test('num returns true for numbers', t => {
@@ -265,7 +266,7 @@ test('array values longer than breakpoints does not reset returned style object'
   const a = width({
     width: ['100%', , , , , '50%', '25%'],
   })
-  t.deepEqual(a, [{ width: '100%' }])
+  t.deepEqual(a, { width: '100%' })
 })
 
 test('mapProps copies propTypes', t => {
@@ -273,3 +274,16 @@ test('mapProps copies propTypes', t => {
   const func = mapProps(props => props)(margin)
   t.is(typeof func.propTypes, 'object')
 })
+
+test('merge deeply merges', t => {
+  const result = merge(
+    { hello: { hi: 'beep' } },
+    { hello: { hey: 'boop' } },
+  )
+  t.deepEqual(result, {
+    hello: {
+      hi: 'beep',
+      hey: 'boop',
+    }
+  })
+})
diff --git a/test/styles.js b/test/styles.js
index d90129bd7..60fcf6ace 100644
--- a/test/styles.js
+++ b/test/styles.js
@@ -22,7 +22,7 @@ const theme = {
 
 test('returns color values from theme', t => {
   const a = color({ theme, color: 'blue', bg: 'black' })
-  t.deepEqual(a, [{ color: '#07c' }, { backgroundColor: '#111' }])
+  t.deepEqual(a, { color: '#07c', backgroundColor: '#111' })
 })
 
 test('returns raw color values', t => {
@@ -31,7 +31,7 @@ test('returns raw color values', t => {
     color: 'inherit',
     bg: 'tomato',
   })
-  t.deepEqual(a, [{ color: 'inherit' }, { backgroundColor: 'tomato' }])
+  t.deepEqual(a, { color: 'inherit', backgroundColor: 'tomato' })
 })
 
 test('backgroundColor prop overrides bg prop', t => {
@@ -39,7 +39,7 @@ test('backgroundColor prop overrides bg prop', t => {
     backgroundColor: 'tomato',
     bg: 'blue',
   })
-  t.deepEqual(a, [{ backgroundColor: 'tomato' }])
+  t.deepEqual(a, { backgroundColor: 'tomato' })
 })
 
 test('returns a pixel font-size', t => {
@@ -76,22 +76,22 @@ test('returns an array of style objects', t => {
   const styles = space({
     m: '4px',
   })
-  t.deepEqual(styles, [{ margin: '4px' }])
+  t.deepEqual(styles, { margin: '4px' })
 })
 
 test('returns 0 values', t => {
   const styles = space({ m: 0 })
-  t.deepEqual(styles, [{ margin: 0 }])
+  t.deepEqual(styles, { margin: 0 })
 })
 
 test('returns negative pixel values', t => {
   const styles = space({ m: -2 })
-  t.deepEqual(styles, [{ margin: '-8px' }])
+  t.deepEqual(styles, { margin: '-8px' })
 })
 
 test('returns negative em values', t => {
   const styles = space({ m: '-16em' })
-  t.deepEqual(styles, [{ margin: '-16em' }])
+  t.deepEqual(styles, { margin: '-16em' })
 })
 
 test('returns negative theme values', t => {
@@ -101,7 +101,7 @@ test('returns negative theme values', t => {
     },
     m: -2,
   })
-  t.deepEqual(styles, [{ margin: '-8px' }])
+  t.deepEqual(styles, { margin: '-8px' })
 })
 
 test('returns positive theme values', t => {
@@ -111,27 +111,25 @@ test('returns positive theme values', t => {
     },
     m: 2,
   })
-  t.deepEqual(styles, [{ margin: '2em' }])
+  t.deepEqual(styles, { margin: '2em' })
 })
 
 test('returns responsive values', t => {
   const styles = space({
     m: [0, 2, 3],
   })
-  t.deepEqual(styles, [
-    [
-      { margin: 0 },
-      { '@media screen and (min-width: 40em)': { margin: '8px' } },
-      { '@media screen and (min-width: 52em)': { margin: '16px' } },
-    ],
-  ])
+  t.deepEqual(styles, {
+      margin: 0,
+      '@media screen and (min-width: 40em)': { margin: '8px' },
+      '@media screen and (min-width: 52em)': { margin: '16px' },
+  })
 })
 
 test('returns aliased values', t => {
   const styles = space({
     px: 2,
   })
-  t.deepEqual(styles, [{ paddingLeft: '8px' }, { paddingRight: '8px' }])
+  t.deepEqual(styles, { paddingLeft: '8px', paddingRight: '8px' })
 })
 
 test('returns string values from theme', t => {
@@ -141,7 +139,7 @@ test('returns string values from theme', t => {
     },
     padding: 1,
   })
-  t.deepEqual(styles, [{ padding: '1em' }])
+  t.deepEqual(styles, { padding: '1em' })
 })
 
 test('returns negative string values from theme', t => {
@@ -151,7 +149,7 @@ test('returns negative string values from theme', t => {
     },
     margin: -1,
   })
-  t.deepEqual(styles, [{ margin: '-1em' }])
+  t.deepEqual(styles, { margin: '-1em' })
 })
 
 test('returns values from theme object', t => {
@@ -162,17 +160,17 @@ test('returns values from theme object', t => {
     margin: 'sm',
   })
 
-  t.deepEqual(styles, [{ margin: '1px' }])
+  t.deepEqual(styles, { margin: '1px' })
 })
 
 test('pl prop sets paddingLeft', t => {
   const styles = space({ pl: 2 })
-  t.deepEqual(styles, [{ paddingLeft: '8px' }])
+  t.deepEqual(styles, { paddingLeft: '8px' })
 })
 
 test('pl prop sets paddingLeft 0', t => {
   const styles = space({ pl: 0 })
-  t.deepEqual(styles, [{ paddingLeft: 0 }])
+  t.deepEqual(styles, { paddingLeft: 0 })
 })
 
 test('px prop overrides pl prop', t => {
@@ -180,7 +178,7 @@ test('px prop overrides pl prop', t => {
     pl: 1,
     px: 2,
   })
-  t.deepEqual(styles, [{ paddingLeft: '8px' }, { paddingRight: '8px' }])
+  t.deepEqual(styles, { paddingLeft: '8px', paddingRight: '8px' })
 })
 
 test('py prop overrides pb prop', t => {
@@ -188,7 +186,7 @@ test('py prop overrides pb prop', t => {
     pb: 1,
     py: 2,
   })
-  t.deepEqual(styles, [{ paddingTop: '8px' }, { paddingBottom: '8px' }])
+  t.deepEqual(styles, { paddingTop: '8px', paddingBottom: '8px' })
 })
 
 test('mx prop overrides mr prop', t => {
@@ -196,7 +194,7 @@ test('mx prop overrides mr prop', t => {
     mr: 1,
     mx: 2,
   })
-  t.deepEqual(styles, [{ marginLeft: '8px' }, { marginRight: '8px' }])
+  t.deepEqual(styles, { marginLeft: '8px', marginRight: '8px' })
 })
 
 test('my prop overrides mt prop', t => {
@@ -204,7 +202,7 @@ test('my prop overrides mt prop', t => {
     mt: 1,
     my: 2,
   })
-  t.deepEqual(styles, [{ marginTop: '8px' }, { marginBottom: '8px' }])
+  t.deepEqual(styles, { marginTop: '8px', marginBottom: '8px' })
 })
 
 test('margin overrides m prop', t => {
@@ -212,7 +210,7 @@ test('margin overrides m prop', t => {
     m: 1,
     margin: 2,
   })
-  t.deepEqual(styles, [{ margin: '8px' }])
+  t.deepEqual(styles, { margin: '8px' })
 })
 
 test('space includes propTypes', t => {
@@ -225,7 +223,7 @@ test('size returns width and height', t => {
   const styles = size({
     size: 4,
   })
-  t.deepEqual(styles, [{ width: '4px' }, { height: '4px' }])
+  t.deepEqual(styles, { width: '4px', height: '4px' })
 })
 
 // grid
@@ -332,10 +330,10 @@ test('borders prop returns correct sequence', t => {
     borderStyle: 'dashed',
     borderColor: 'red',
   })
-  t.deepEqual(a, [
-    { borderBottom: '1px solid' },
-    { borderWidth: '2px' },
-    { borderStyle: 'dashed' },
-    { borderColor: 'red' },
-  ])
+  t.deepEqual(a, {
+    borderBottom: '1px solid',
+    borderWidth: '2px',
+    borderStyle: 'dashed',
+    borderColor: 'red',
+  })
 })