diff --git a/build/lib/extensions.js b/build/lib/extensions.js
index fe6c2445662..a2602610175 100644
--- a/build/lib/extensions.js
+++ b/build/lib/extensions.js
@@ -373,10 +373,27 @@ function packageLocalExtensionsStream(forWeb, disableMangle) {
         .filter(({ name }) => excludedExtensions.indexOf(name) === -1)
         .filter(({ name }) => builtInExtensions.every(b => b.name !== name))
         .filter(({ manifestPath }) => (forWeb ? isWebExtension(require(manifestPath)) : true)));
-    const localExtensionsStream = minifyExtensionResources(es.merge(...localExtensionsDescriptions.map(extension => {
-        return fromLocal(extension.path, forWeb, disableMangle)
-            .pipe(rename(p => p.dirname = `extensions/${extension.name}/${p.dirname}`));
-    })));
+    // --- Start Positron ---
+    // Process the local extensions serially to avoid running out of file
+    // descriptors (EMFILE) when building.
+    const localExtensionsStream = es.through();
+    const queue = [...localExtensionsDescriptions];
+    function processNext() {
+        if (queue.length === 0) {
+            localExtensionsStream.end();
+            return;
+        }
+        const extension = queue.shift();
+        if (!extension) {
+            return;
+        }
+        const stream = fromLocal(extension.path, forWeb, disableMangle)
+            .pipe(rename(p => p.dirname = `extensions/${extension.name}/${p.dirname}`))
+            .pipe(es.through(undefined, processNext));
+        stream.pipe(localExtensionsStream, { end: false });
+    }
+    processNext();
+    // --- End Positron ---
     let result;
     if (forWeb) {
         result = localExtensionsStream;
diff --git a/build/lib/extensions.ts b/build/lib/extensions.ts
index 470b2d61132..508928335b9 100644
--- a/build/lib/extensions.ts
+++ b/build/lib/extensions.ts
@@ -427,14 +427,34 @@ export function packageLocalExtensionsStream(forWeb: boolean, disableMangle: boo
 			.filter(({ name }) => builtInExtensions.every(b => b.name !== name))
 			.filter(({ manifestPath }) => (forWeb ? isWebExtension(require(manifestPath)) : true))
 	);
-	const localExtensionsStream = minifyExtensionResources(
-		es.merge(
-			...localExtensionsDescriptions.map(extension => {
-				return fromLocal(extension.path, forWeb, disableMangle)
-					.pipe(rename(p => p.dirname = `extensions/${extension.name}/${p.dirname}`));
-			})
-		)
-	);
+
+	// --- Start Positron ---
+
+	// Process the local extensions serially to avoid running out of file
+	// descriptors (EMFILE) when building.
+
+	const localExtensionsStream = es.through();
+	const queue = [...localExtensionsDescriptions];
+
+	function processNext() {
+		if (queue.length === 0) {
+			localExtensionsStream.end();
+			return;
+		}
+
+		const extension = queue.shift();
+		if (!extension) {
+			return;
+		}
+		const stream = fromLocal(extension.path, forWeb, disableMangle)
+			.pipe(rename(p => p.dirname = `extensions/${extension.name}/${p.dirname}`))
+			.pipe(es.through(undefined, processNext));
+
+		stream.pipe(localExtensionsStream, { end: false });
+	}
+
+	processNext();
+	// --- End Positron ---
 
 	let result: Stream;
 	if (forWeb) {