diff --git a/apps/rush-lib/src/utilities/Utilities.ts b/apps/rush-lib/src/utilities/Utilities.ts
index a2e5ebc29de..82bbb323bd3 100644
--- a/apps/rush-lib/src/utilities/Utilities.ts
+++ b/apps/rush-lib/src/utilities/Utilities.ts
@@ -774,7 +774,8 @@ export class Utilities {
       stdio: stdio,
       env: keepEnvironment
         ? environment
-        : Utilities._createEnvironmentForRushCommand({ initialEnvironment: environment })
+        : Utilities._createEnvironmentForRushCommand({ initialEnvironment: environment }),
+      maxBuffer: 10 * 1024 * 1024 // Set default max buffer size to 10MB
     };
 
     // This is needed since we specify shell=true below.
diff --git a/common/changes/@microsoft/rush/feat-increase-maxBuffer_2021-12-21-03-55.json b/common/changes/@microsoft/rush/feat-increase-maxBuffer_2021-12-21-03-55.json
new file mode 100644
index 00000000000..992272b09ae
--- /dev/null
+++ b/common/changes/@microsoft/rush/feat-increase-maxBuffer_2021-12-21-03-55.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "Fix an issue that occurs when running a command with a selection argument with a Git ref (like `--from git:main`) in a repo with a pnpm lockfile larger than 1MB.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}
\ No newline at end of file