diff --git a/package.json b/package.json
index 60747686..83bace70 100644
--- a/package.json
+++ b/package.json
@@ -62,7 +62,7 @@
     "escape-string-regexp": "1.0.5",
     "source-map": "0.5.6",
     "string-hash": "1.1.1",
-    "stylis": "3.0.17"
+    "stylis": "3.1.5"
   },
   "devDependencies": {
     "ava": "0.19.1",
diff --git a/src/_utils.js b/src/_utils.js
index 8182b323..e33467e8 100644
--- a/src/_utils.js
+++ b/src/_utils.js
@@ -58,18 +58,14 @@ export const getExpressionText = expr => {
   // e.g.
   // p { color: ${myConstant}; }
   // becomes
-  // p { color: var(--styled-jsx-expression-${id}--); }
-  //
-  // We use a dummy custom property so that the resulting css
-  // passes the css validation which is needed to detect
-  // external styles.
+  // p { color: %%styled-jsx-placeholder-${id}%%; }
 
   const replacements = expressions
     .map((e, id) => ({
       pattern: new RegExp(
         `\\$\\{\\s*${escapeStringRegExp(e.getSource())}\\s*\\}`
       ),
-      replacement: `var(--styled-jsx-expression-${id}--)`,
+      replacement: `%%styled-jsx-placeholder-${id}%%`,
       initial: `$\{${e.getSource()}}`
     }))
     .sort((a, b) => a.initial.length < b.initial.length)
@@ -94,7 +90,7 @@ export const getExpressionText = expr => {
 export const restoreExpressions = (css, replacements) =>
   replacements.reduce((css, currentReplacement) => {
     css = css.replace(
-      new RegExp(escapeStringRegExp(currentReplacement.replacement), 'g'),
+      new RegExp(currentReplacement.replacement, 'g'),
       currentReplacement.initial
     )
     return css
@@ -197,7 +193,49 @@ export const generateAttribute = (name, value) =>
 
 export const isValidCss = str => {
   try {
-    parseCss(str)
+    parseCss(
+      // Replace the placeholders with some valid CSS
+      // so that parsing doesn't fail for otherwise valid CSS.
+      str
+        // Replace all the placeholders with `all`
+        .replace(
+          // `\S` (the `delimiter`) is to match
+          // the beginning of a block `{`
+          // a property `:`
+          // or the end of a property `;`
+          /(\S)?\s*%%styled-jsx-placeholder-[^%]+%%(?:\s*(\}))?/gi,
+          (match, delimiter, isBlockEnd) => {
+            // The `end` of the replacement would be
+            let end
+
+            if (delimiter === ':' && isBlockEnd) {
+              // ';}' single property block without semicolon
+              // E.g. { color: all;}
+              end = `;}`
+            } else if (delimiter === '{' || isBlockEnd) {
+              // ':;' when we are at the beginning or the end of a block
+              // E.g. { all:; ...otherstuff
+              // E.g. all:; }
+              end = `:;${isBlockEnd || ''}`
+            } else if (delimiter === ';') {
+              // ':' when we are inside of a block
+              // E.g. color: red; all:; display: block;
+              end = ':'
+            } else {
+              // Otherwise empty
+              end = ''
+            }
+
+            return `${delimiter || ''}all${end}`
+          }
+        )
+        // Replace block placeholders before media queries
+        // E.g. all @media (all) {}
+        .replace(/all\s*([@])/g, (match, delimiter) => `all {} ${delimiter}`)
+        // Replace block placeholders at the beginning of a media query block
+        // E.g. @media (all) { all:; div { ... }}
+        .replace(/@media[^{]+{\s*all:;/g, '@media (all) { ')
+    )
     return true
   } catch (err) {}
   return false
diff --git a/test/__snapshots__/external.js.snap b/test/__snapshots__/external.js.snap
index f1e8501c..e85fcd33 100644
--- a/test/__snapshots__/external.js.snap
+++ b/test/__snapshots__/external.js.snap
@@ -14,15 +14,26 @@ exports[`transpiles external stylesheets 1`] = `
 
 export const foo = new String(\`div{color:\${color}}\`);
 
-foo.__hash = '1882068550';
-foo.__scoped = \`div[data-jsx-ext~=\\"2882068550\\"]{color:\${color}}\`;
-foo.__scopedHash = '2882068550';
+foo.__hash = '166851635';
+foo.__scoped = \`div[data-jsx-ext~=\\"266851635\\"]{color:\${color}}\`;
+foo.__scopedHash = '266851635';
 
 var __styledJsxDefaultExport = new String(\`div{font-size:3em}p{color:\${color}}\`);
 
-__styledJsxDefaultExport.__hash = '12515736096';
-__styledJsxDefaultExport.__scoped = \`div[data-jsx-ext~=\\"22515736096\\"]{font-size:3em}p[data-jsx-ext~=\\"22515736096\\"]{color:\${color}}\`;
-__styledJsxDefaultExport.__scopedHash = '22515736096';
+__styledJsxDefaultExport.__hash = '12602670606';
+__styledJsxDefaultExport.__scoped = \`div[data-jsx-ext~=\\"22602670606\\"]{font-size:3em}p[data-jsx-ext~=\\"22602670606\\"]{color:\${color}}\`;
+__styledJsxDefaultExport.__scopedHash = '22602670606';
+export default __styledJsxDefaultExport;"
+`;
+
+exports[`transpiles external stylesheets with validation (expressions) 1`] = `
+"const expr = 'test';
+
+var __styledJsxDefaultExport = new String(\`\${expr} \${expr} \${expr},div{display:\${expr};color:\${expr};\${expr};\${expr} \${expr};background:red;-webkit-animation:\${expr} 10s ease-out;animation:\${expr} 10s ease-out}div{color:red;\${expr}}div{color:red;\${expr}}@media (\${expr}){\${expr} span.\${expr}{color:red}\${expr} \${expr}{color:red}\${expr},\${expr}{color:red}\${expr} div,\${expr}{color:red}}@media (min-width:\${expr}){div.\${expr}{color:red}all\${expr}{\${expr} color:red}}@font-face{\${expr}}\`);
+
+__styledJsxDefaultExport.__hash = '12538838655';
+__styledJsxDefaultExport.__scoped = \`\${expr}[data-jsx-ext~=\\"22538838655\\"] \${expr}[data-jsx-ext~=\\"22538838655\\"] \${expr}[data-jsx-ext~=\\"22538838655\\"],div[data-jsx-ext~=\\"22538838655\\"]{display:\${expr};color:\${expr};\${expr};\${expr} \${expr};background:red;-webkit-animation:\${expr} 10s ease-out;animation:\${expr} 10s ease-out}div[data-jsx-ext~=\\"22538838655\\"]{color:red;\${expr}}div[data-jsx-ext~=\\"22538838655\\"]{color:red;\${expr}}@media (\${expr}){\${expr} span.\${expr}[data-jsx-ext~=\\"22538838655\\"]{color:red}\${expr} \${expr}[data-jsx-ext~=\\"22538838655\\"]{color:red}\${expr}[data-jsx-ext~=\\"22538838655\\"],\${expr}[data-jsx-ext~=\\"22538838655\\"]{color:red}\${expr} div[data-jsx-ext~=\\"22538838655\\"],\${expr}[data-jsx-ext~=\\"22538838655\\"]{color:red}}@media (min-width:\${expr}){div.\${expr}[data-jsx-ext~=\\"22538838655\\"]{color:red}all\${expr}[data-jsx-ext~=\\"22538838655\\"]{\${expr} color:red}}@font-face{\${expr}}\`;
+__styledJsxDefaultExport.__scopedHash = '22538838655';
 export default __styledJsxDefaultExport;"
 `;
 
@@ -31,14 +42,53 @@ exports[`transpiles external stylesheets with validation 1`] = `
 
 export const foo = new String(\`div{color:\${color}}\`);
 
-foo.__hash = '1882068550';
-foo.__scoped = \`div[data-jsx-ext~=\\"2882068550\\"]{color:\${color}}\`;
-foo.__scopedHash = '2882068550';
+foo.__hash = '166851635';
+foo.__scoped = \`div[data-jsx-ext~=\\"266851635\\"]{color:\${color}}\`;
+foo.__scopedHash = '266851635';
 
 var __styledJsxDefaultExport = new String(\`div{font-size:3em}p{color:\${color}}\`);
 
-__styledJsxDefaultExport.__hash = '12515736096';
-__styledJsxDefaultExport.__scoped = \`div[data-jsx-ext~=\\"22515736096\\"]{font-size:3em}p[data-jsx-ext~=\\"22515736096\\"]{color:\${color}}\`;
-__styledJsxDefaultExport.__scopedHash = '22515736096';
+__styledJsxDefaultExport.__hash = '12602670606';
+__styledJsxDefaultExport.__scoped = \`div[data-jsx-ext~=\\"22602670606\\"]{font-size:3em}p[data-jsx-ext~=\\"22602670606\\"]{color:\${color}}\`;
+__styledJsxDefaultExport.__scopedHash = '22602670606';
 export default __styledJsxDefaultExport;"
 `;
+
+exports[`transpiles external stylesheets with validation 2`] = `
+"const expr = 'test';
+
+export const expressionsTest = \`
+  div {
+  display: \${expr};
+    color: \${expr};
+    \${expr};
+    \${expr}
+    \${expr};
+    background: red;
+  animation: \${expr} 10s ease-out;
+  }
+
+  @media (\${expr}) {
+   div.\${expr} {
+    color: red;
+   }
+   \${expr}
+  \${expr} {
+    color: red;
+  }
+  }
+
+  @media (min-width: \${expr}) {
+   div.\${expr} {
+    color: red;
+   }
+  all\${expr} {
+    color: red;
+  }
+  }
+
+  @font-face {
+    \${expr}
+  }
+\`;"
+`;
diff --git a/test/__snapshots__/index.js.snap b/test/__snapshots__/index.js.snap
index c4f4e62e..3c632c15 100644
--- a/test/__snapshots__/index.js.snap
+++ b/test/__snapshots__/index.js.snap
@@ -5,7 +5,7 @@ exports[`generates source maps 1`] = `
 export default (() => <div data-jsx={188072295}>
     <p data-jsx={188072295}>test</p>
     <p data-jsx={188072295}>woot</p>
-    <_JSXStyle styleId={188072295} css={\\"p[data-jsx=\\\\\\"188072295\\\\\\"]{color:red}\\\\n/*# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbXSwibmFtZXMiOltdLCJtYXBwaW5ncyI6IiIsImZpbGUiOiJzb3VyY2UtbWFwcy5qcyIsInNvdXJjZXNDb250ZW50IjpbXX0= */\\\\n/*@ sourceURL=source-maps.js */\\"} />
+    <_JSXStyle styleId={188072295} css={\\"p[data-jsx=\\\\\\"188072295\\\\\\"]{color:red}\\\\n/*# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbInNvdXJjZS1tYXBzLmpzIl0sIm5hbWVzIjpbXSwibWFwcGluZ3MiOiJBQUlnQixBQUNjLFdBQUMiLCJmaWxlIjoic291cmNlLW1hcHMuanMiLCJzb3VyY2VzQ29udGVudCI6WyJleHBvcnQgZGVmYXVsdCAoKSA9PiAoXG4gIDxkaXY+XG4gICAgPHA+dGVzdDwvcD5cbiAgICA8cD53b290PC9wPlxuICAgIDxzdHlsZSBqc3g+eydwIHsgY29sb3I6IHJlZCB9J308L3N0eWxlPlxuICA8L2Rpdj5cbilcbiJdfQ== */\\\\n/*@ sourceURL=source-maps.js */\\"} />
   </div>);"
 `;
 
@@ -92,19 +92,19 @@ const animationName = 'my-cool-animation';
 const obj = { display: 'block' };
 
 // eslint-disable-next-line no-unused-vars
-export default (({ display }) => <div data-jsx={290536030}>
-    <p data-jsx={290536030}>test</p>
-    <_JSXStyle styleId={2129566164} css={\`p.\${color}[data-jsx=\\"290536030\\"]{color:\${otherColor};display:\${obj.display}}\`} />
-    <_JSXStyle styleId={188072295} css={\\"p[data-jsx=\\\\\\"290536030\\\\\\"]{color:red}\\"} />
+export default (({ display }) => <div data-jsx={4091813028}>
+    <p data-jsx={4091813028}>test</p>
+    <_JSXStyle styleId={2129566164} css={\`p.\${color}[data-jsx=\\"4091813028\\"]{color:\${otherColor};display:\${obj.display}}\`} />
+    <_JSXStyle styleId={188072295} css={\\"p[data-jsx=\\\\\\"4091813028\\\\\\"]{color:red}\\"} />
     <_JSXStyle styleId={806016056} css={\`body{background:\${color}}\`} />
     <_JSXStyle styleId={806016056} css={\`body{background:\${color}}\`} />
-    <_JSXStyle styleId={924167211} css={\`p[data-jsx=\\"290536030\\"]{color:\${color}}\`} />
-    <_JSXStyle styleId={924167211} css={\`p[data-jsx=\\"290536030\\"]{color:\${color}}\`} />
-    <_JSXStyle styleId={3469794077} css={\`p[data-jsx=\\"290536030\\"]{color:\${darken(color)}}\`} />
-    <_JSXStyle styleId={945380644} css={\`p[data-jsx=\\"290536030\\"]{color:\${darken(color) + 2}}\`} />
-    <_JSXStyle styleId={4106311606} css={\`@media (min-width:\${mediumScreen}){p[data-jsx=\\"290536030\\"]{color:green}p[data-jsx=\\"290536030\\"]{color \${\`red\`}}}p[data-jsx=\\"290536030\\"]{color:red}\`} />
-    <_JSXStyle styleId={2369334310} css={\`p[data-jsx=\\"290536030\\"]{-webkit-animation-duration:\${animationDuration};animation-duration:\${animationDuration}}\`} />
-    <_JSXStyle styleId={3168033860} css={\`p[data-jsx=\\"290536030\\"]{-webkit-animation:\${animationDuration} forwards \${animationName};animation:\${animationDuration} forwards \${animationName}}\`} />
+    <_JSXStyle styleId={924167211} css={\`p[data-jsx=\\"4091813028\\"]{color:\${color}}\`} />
+    <_JSXStyle styleId={924167211} css={\`p[data-jsx=\\"4091813028\\"]{color:\${color}}\`} />
+    <_JSXStyle styleId={3469794077} css={\`p[data-jsx=\\"4091813028\\"]{color:\${darken(color)}}\`} />
+    <_JSXStyle styleId={945380644} css={\`p[data-jsx=\\"4091813028\\"]{color:\${darken(color) + 2}}\`} />
+    <_JSXStyle styleId={3617592140} css={\`@media (min-width:\${mediumScreen}){p[data-jsx=\\"4091813028\\"]{color:green}p[data-jsx=\\"4091813028\\"]{color:\${\`red\`}}}p[data-jsx=\\"4091813028\\"]{color:red}\`} />
+    <_JSXStyle styleId={2369334310} css={\`p[data-jsx=\\"4091813028\\"]{-webkit-animation-duration:\${animationDuration};animation-duration:\${animationDuration}}\`} />
+    <_JSXStyle styleId={3168033860} css={\`p[data-jsx=\\"4091813028\\"]{-webkit-animation:\${animationDuration} forwards \${animationName};animation:\${animationDuration} forwards \${animationName}}\`} />
   </div>);"
 `;
 
diff --git a/test/external.js b/test/external.js
index 5a7a711b..7cdbd37a 100644
--- a/test/external.js
+++ b/test/external.js
@@ -29,3 +29,11 @@ test('transpiles external stylesheets with validation', async t => {
   t.regex(code, new RegExp(escapeStringRegExp(MARKUP_ATTRIBUTE_EXTERNAL), 'g'))
   t.snapshot(code)
 })
+
+test('transpiles external stylesheets with validation (expressions)', async t => {
+  const { code } = await transform('./fixtures/styles-expressions.js', {
+    validate: true
+  })
+  t.regex(code, new RegExp(escapeStringRegExp(MARKUP_ATTRIBUTE_EXTERNAL), 'g'))
+  t.snapshot(code)
+})
diff --git a/test/fixtures/expressions.js b/test/fixtures/expressions.js
index 8efb86cf..53a1524a 100644
--- a/test/fixtures/expressions.js
+++ b/test/fixtures/expressions.js
@@ -23,7 +23,7 @@ export default ({ display }) => (
     <style jsx>{`
       @media (min-width: ${mediumScreen}) {
         p { color: green }
-        p { color ${`red`}}
+        p { color: ${`red`}}
       }
       p { color: red }`}</style>
     <style jsx>{`p { animation-duration: ${animationDuration} }`}</style>
diff --git a/test/fixtures/styles-expressions.js b/test/fixtures/styles-expressions.js
new file mode 100644
index 00000000..10720074
--- /dev/null
+++ b/test/fixtures/styles-expressions.js
@@ -0,0 +1,60 @@
+const expr = 'test'
+
+export default `${expr} ${expr} ${expr},
+  div {
+  display: ${expr};
+    color: ${expr};
+    ${expr};
+    ${expr}
+    ${expr};
+    background: red;
+  animation: ${expr} 10s ease-out;
+  }
+
+   div {
+  color: red;
+${expr}
+}
+
+div {
+  color: red;
+${expr};
+}
+
+  @media (${expr}) {
+
+${expr}
+   span.${expr} {
+    color: red;
+   }
+
+${expr}
+
+  ${expr} {
+    color: red;
+  }
+    ${expr}, ${expr} {
+      color: red;
+    }
+
+   ${expr}
+
+    div, ${expr} {
+      color: red;
+    }
+  }
+
+
+  @media (min-width: ${expr}) {
+   div.${expr} {
+    color: red;
+   }
+  all${expr} {
+${expr}
+    color: red;
+  }
+  }
+
+  @font-face {
+    ${expr}
+}`
diff --git a/test/fixtures/styles.js b/test/fixtures/styles.js
index bde1d077..b76deb25 100644
--- a/test/fixtures/styles.js
+++ b/test/fixtures/styles.js
@@ -4,5 +4,5 @@ export const foo = `div { color: ${color}}`
 
 export default `
   div { font-size: 3em }
-  p { color: ${color}}
+  p { color: ${color};}
 `
diff --git a/yarn.lock b/yarn.lock
index 32d2d0d6..55fa6b1e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -4625,9 +4625,9 @@ strip-json-comments@~2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/strip-json-comments/-/strip-json-comments-2.0.1.tgz#3c531942e908c2697c0ec344858c286c7ca0a60a"
 
-stylis@3.0.17:
-  version "3.0.17"
-  resolved "https://registry.yarnpkg.com/stylis/-/stylis-3.0.17.tgz#978643aed384f2138c54af9c02adeb61f1aa75f6"
+stylis@3.1.5:
+  version "3.1.5"
+  resolved "https://registry.yarnpkg.com/stylis/-/stylis-3.1.5.tgz#c585186286aaa79856c9ac62bbb38113923edda3"
 
 supports-color@^2.0.0:
   version "2.0.0"