diff --git a/chrome/content/zotero/xpcom/utilities_internal.js b/chrome/content/zotero/xpcom/utilities_internal.js
index 5356821b29..4131d75256 100644
--- a/chrome/content/zotero/xpcom/utilities_internal.js
+++ b/chrome/content/zotero/xpcom/utilities_internal.js
@@ -139,14 +139,28 @@ Zotero.Utilities.Internal = {
 	
 	/**
 	 * @param {nsIFile|String} file  File or file path
-	 * @param {Boolean} [base64=FALSE]  Return as base-64-encoded string
-	 *                                  rather than hex string
 	 */
-	md5Async: async function (file, base64) {
+	md5Async: async function (file) {
 		function toHexString(charCode) {
 			return ("0" + charCode.toString(16)).slice(-2);
 		}
 		
+		var file = Zotero.File.pathToFile(file);
+		try {
+			let { size } = await IOUtils.stat(file.path);
+			if (size === 0) {
+				// MD5 for empty string
+				return "d41d8cd98f00b204e9800998ecf8427e";
+			}
+		}
+		catch (e) {
+			// Return false for missing files
+			if (e.name == "NotFoundError") {
+				return false;
+			}
+			throw e;
+		}
+		
 		var ch = Components.classes["@mozilla.org/security/hash;1"]
 			.createInstance(Components.interfaces.nsICryptoHash);
 		ch.init(ch.MD5);
@@ -156,12 +170,8 @@ Zotero.Utilities.Internal = {
 				.createInstance(Ci.nsIFileInputStream);
 			is.init(Zotero.File.pathToFile(file), -1, -1, Ci.nsIFileInputStream.CLOSE_ON_EOF);
 			ch.updateFromStream(is, -1);
-			let hash = ch.finish(base64);
-			// Base64
-			if (base64) {
-				return hash;
-			}
-			// Hex string
+			// Get binary string and convert to hex string
+			let hash = ch.finish(false);
 			let hexStr = "";
 			for (let i = 0; i < hash.length; i++) {
 				hexStr += toHexString(hash.charCodeAt(i));
diff --git a/test/tests/utilities_internalTest.js b/test/tests/utilities_internalTest.js
index f7f0c4d2cd..d2f209cb1e 100644
--- a/test/tests/utilities_internalTest.js
+++ b/test/tests/utilities_internalTest.js
@@ -44,6 +44,24 @@ describe("Zotero.Utilities.Internal", function () {
 			
 			yield OS.File.remove(file);
 		});
+		
+		it("should return false for a nonexistent file", async function () {
+			var tmpDir = Zotero.getTempDirectory().path;
+			var file = OS.Path.join(tmpDir, 'nonexistent-asawefaweoihafa');
+			await assert.eventually.isFalse(ZUI.md5Async(file));
+		});
+		
+		it("should return hash for an empty file", async function () {
+			const emptyHash = 'd41d8cd98f00b204e9800998ecf8427e';
+			
+			var tmpDir = Zotero.getTempDirectory().path;
+			var file = OS.Path.join(tmpDir, 'empty-file');
+			await IOUtils.write(file, new Uint8Array());
+			
+			await assert.eventually.equal(ZUI.md5Async(file), emptyHash);
+			
+			await IOUtils.remove(file);
+		});
 	})