diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index c534381..7fbd945 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -15,4 +15,21 @@ jobs:
           pattern: '[\w\d/]*v(\d+(?:\.\d+)*)'
           replace-with: '$1'
       - name: Check equality
-        run: '[[ "${{ steps.test.outputs.replaced }}" == "1.0.1" ]]'
\ No newline at end of file
+        run: '[[ "${{ steps.test.outputs.replaced }}" == "1.0.1" ]]'
+  test-json:
+    runs-on: ubuntu-latest
+    name: Test
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v1
+      - name: Test
+        uses: ./
+        id: test
+        with:
+          string: '_replace_underscores_'
+          pattern: '_'
+          replace-with: '" "'
+          flags: 'g'
+          json: true
+      - name: Check equality
+        run: '[[ "${{ steps.test.outputs.replaced }}" == " replace underscores " ]]'
\ No newline at end of file
diff --git a/README.md b/README.md
index 56a3c97..65dcd6f 100644
--- a/README.md
+++ b/README.md
@@ -1,37 +1,41 @@
-# `replace-string` GitHub Action
-
-Replaces strings with regular expressions.
-
-## Inputs
-
-### `pattern`
-
-**Required** Regular expression to match.
-
-### `string`
-
-**Required** Input string.
-
-### `replace-with`
-
-**Required** String to use for replacement.
-
-### `flags`
-
-Flags to use when matching. Please refer to [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp) for more information.
-
-## Outputs
-
-### `replaced`
-
-The replaced string.
-
-## Example usage
-
-```yaml
-uses: frabert/replace-string-action@v1.2
-with:
-  pattern: 'Hello, (\w+)!'
-  string: 'Hello, world!'
-  replace-with: 'I greet you, $1!'
-```
+# `replace-string` GitHub Action
+
+Replaces strings with regular expressions.
+
+## Inputs
+
+### `pattern`
+
+**Required** Regular expression to match.
+
+### `string`
+
+**Required** Input string.
+
+### `replace-with`
+
+**Required** String to use for replacement.
+
+### `flags`
+
+Flags to use when matching. Please refer to [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp) for more information.
+
+### `json`
+
+Boolean. Interprets `replace-with` as JSON data. Useful for when `replace-with` contains leading or trailing whitespace that would be trimmed away by GitHub.
+
+## Outputs
+
+### `replaced`
+
+The replaced string.
+
+## Example usage
+
+```yaml
+uses: frabert/replace-string-action@v1.2
+with:
+  pattern: 'Hello, (\w+)!'
+  string: 'Hello, world!'
+  replace-with: 'I greet you, $1!'
+```
diff --git a/action.yml b/action.yml
index 8318dcb..ab3e424 100644
--- a/action.yml
+++ b/action.yml
@@ -1,25 +1,28 @@
-name: 'Replace string'
-author: 'Francesco Bertolaccini'
-description: 'Use regular expressions to manipulate strings'
-inputs:
-  pattern:
-    description: 'Regular expression pattern'
-    required: true
-  string:
-    description: 'The input string'
-    required: true
-  replace-with:
-    description: 'What to replace with'
-    required: true
-  flags:
-    description: 'Flags to use when matching'
-    required: false
-outputs:
-  replaced:
-    description: 'The output string'
-runs:
-  using: 'node12'
-  main: 'index.js'
-branding:
-  icon: 'search'
+name: 'Replace string'
+author: 'Francesco Bertolaccini'
+description: 'Use regular expressions to manipulate strings'
+inputs:
+  pattern:
+    description: 'Regular expression pattern'
+    required: true
+  string:
+    description: 'The input string'
+    required: true
+  replace-with:
+    description: 'What to replace with'
+    required: true
+  flags:
+    description: 'Flags to use when matching'
+    required: false
+  json:
+    description: 'Interprets `replace-with` as JSON data. Useful for when `replace-with` contains leading or trailing whitespace that would be trimmed away by GitHub'
+    required: false
+outputs:
+  replaced:
+    description: 'The output string'
+runs:
+  using: 'node12'
+  main: 'index.js'
+branding:
+  icon: 'search'
   color: gray-dark
\ No newline at end of file
diff --git a/index.js b/index.js
index 6610aa2..23969ad 100644
--- a/index.js
+++ b/index.js
@@ -3,8 +3,13 @@ const core = require('@actions/core');
 try {
   const pattern = core.getInput('pattern');
   const string = core.getInput('string');
-  const replaceWith = core.getInput('replace-with');
+  let replaceWith = core.getInput('replace-with');
   const flags = core.getInput('flags');
+  const json = core.getInput('json');
+
+  if(json) {
+    replaceWith = JSON.parse(replaceWith);
+  }
 
   const regex = new RegExp(pattern, flags);