diff --git a/README.md b/README.md
index cf4fdc6..3c1d061 100644
--- a/README.md
+++ b/README.md
@@ -34,6 +34,7 @@ jobs:
           collapse-diff: false
           timezone: America/Los_Angeles
           timezone-locale: en-US
+          diff-tool: diff -N -u
 
 ```
 
diff --git a/action.yml b/action.yml
index c673c2d..a835226 100644
--- a/action.yml
+++ b/action.yml
@@ -40,6 +40,10 @@ inputs:
     description: 'Time zone locale to use in comment'
     default: 'en-US'
     required: false
+  diff-tool:
+    description: 'Diff tool to use'
+    default: 'diff -N -u'
+    required: false
 runs:
   using: 'node12'
   main: 'dist/index.js'
diff --git a/dist/index.js b/dist/index.js
index 6062753..efcfedf 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -1918,6 +1918,7 @@ const PLAINTEXT = core.getInput('plaintext').toLowerCase() === "true";
 const COLLAPSE_DIFF = core.getInput('collapse-diff').toLowerCase() === "true";
 const TIMEZONE = core.getInput('timezone');
 const TIMEZONE_LOCALE = core.getInput('timezone-locale');
+const DIFF_TOOL = core.getInput('diff-tool') || 'diff -N -u';
 let EXTRA_CLI_ARGS = core.getInput('argocd-extra-cli-args');
 if (PLAINTEXT) {
     EXTRA_CLI_ARGS += ' --plaintext';
@@ -1957,7 +1958,7 @@ function setupArgoCDCommand() {
         fs.chmodSync(path.join(argoBinaryPath), '755');
         // core.addPath(argoBinaryPath);
         return (params) => __awaiter(this, void 0, void 0, function* () {
-            return execCommand(`${argoBinaryPath} ${params} --auth-token=${ARGOCD_TOKEN} --server=${ARGOCD_SERVER_URL} ${EXTRA_CLI_ARGS}`);
+            return execCommand(`KUBECTL_EXTERNAL_DIFF='${DIFF_TOOL}' ${argoBinaryPath} ${params} --auth-token=${ARGOCD_TOKEN} --server=${ARGOCD_SERVER_URL} ${EXTRA_CLI_ARGS}`);
         });
     });
 }
diff --git a/src/main.ts b/src/main.ts
index 89a1e2c..59d3833 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -41,6 +41,7 @@ const PLAINTEXT = core.getInput('plaintext').toLowerCase() === "true";
 const COLLAPSE_DIFF = core.getInput('collapse-diff').toLowerCase() === "true";
 const TIMEZONE = core.getInput('timezone');
 const TIMEZONE_LOCALE = core.getInput('timezone-locale');
+const DIFF_TOOL = core.getInput('diff-tool') || 'diff -N -u';
 let EXTRA_CLI_ARGS = core.getInput('argocd-extra-cli-args');
 if (PLAINTEXT) {
   EXTRA_CLI_ARGS += ' --plaintext';
@@ -87,7 +88,7 @@ async function setupArgoCDCommand(): Promise<(params: string) => Promise<ExecRes
 
   return async (params: string) =>
     execCommand(
-      `${argoBinaryPath} ${params} --auth-token=${ARGOCD_TOKEN} --server=${ARGOCD_SERVER_URL} ${EXTRA_CLI_ARGS}`
+      `KUBECTL_EXTERNAL_DIFF='${DIFF_TOOL}' ${argoBinaryPath} ${params} --auth-token=${ARGOCD_TOKEN} --server=${ARGOCD_SERVER_URL} ${EXTRA_CLI_ARGS}`
     );
 }