diff --git a/chrome/content/zotero/xpcom/attachments.js b/chrome/content/zotero/xpcom/attachments.js
index 4d1c03d5f..798e4a90b 100644
--- a/chrome/content/zotero/xpcom/attachments.js
+++ b/chrome/content/zotero/xpcom/attachments.js
@@ -874,7 +874,12 @@ Zotero.Attachments = new function(){
 		if (Zotero.File.directoryContains(basePath, path)) {
 			basePath = OS.Path.normalize(basePath);
 			path = OS.Path.normalize(path);
-			path = this.BASE_PATH_PLACEHOLDER + path.substr(basePath.length + 1)
+			path = this.BASE_PATH_PLACEHOLDER
+				+ path.substr(basePath.length + 1)
+				// Since stored paths can be synced to other platforms, use
+				// forward slashes for consistency. resolveRelativePath() will
+				// convert to the appropriate platform-specific slash on use.
+				.replace(/\\/g, "/");
 		}
 		
 		return path;
@@ -898,10 +903,15 @@ Zotero.Attachments = new function(){
 			return false;
 		}
 		
-		return OS.Path.join(
+		return this.fixPathSlashes(OS.Path.join(
 			OS.Path.normalize(basePath),
 			path.substr(Zotero.Attachments.BASE_PATH_PLACEHOLDER.length)
-		);
+		));
+	}
+	
+	
+	this.fixPathSlashes = function (path) {
+		return path.replace(Zotero.isWin ? /\//g : /\\/g, Zotero.isWin ? "\\" : "/");
 	}
 	
 	
diff --git a/chrome/content/zotero/xpcom/schema.js b/chrome/content/zotero/xpcom/schema.js
index 046d7d3c7..50adb1abc 100644
--- a/chrome/content/zotero/xpcom/schema.js
+++ b/chrome/content/zotero/xpcom/schema.js
@@ -2274,7 +2274,10 @@ Zotero.Schema = new function(){
 	var _migrateUserData_80_filePaths = Zotero.Promise.coroutine(function* () {
 		var rows = yield Zotero.DB.queryAsync("SELECT itemID, libraryID, key, linkMode, path FROM items JOIN itemAttachments USING (itemID) WHERE path != ''");
 		var tmpDirFile = Zotero.getTempDirectory();
-		var tmpFilePath = OS.Path.normalize(tmpDirFile.path);
+		var tmpFilePath = OS.Path.normalize(tmpDirFile.path)
+			// Since relative paths can be applied on different platforms,
+			// just use "/" everywhere for oonsistency, and convert on use
+			.replace(/\\/g, '/');
 		
 		for (let i = 0; i < rows.length; i++) {
 			let row = rows[i];
@@ -2286,7 +2289,7 @@ Zotero.Schema = new function(){
 				let relPath = path.substr(prefix.length)
 				let file = tmpDirFile.clone();
 				file.setRelativeDescriptor(file, relPath);
-				path = OS.Path.normalize(file.path);
+				path = OS.Path.normalize(file.path).replace(/\\/g, '/');
 				
 				// setRelativeDescriptor() silently uses the parent directory on Windows
 				// if the filename contains certain characters, so strip them —
@@ -2308,12 +2311,9 @@ Zotero.Schema = new function(){
 					}
 				}
 				
-				// Normalize path, and then convert '\' to '/'. As long as normalize() is run on the
-				// path before use, it doesn't matter which separator it uses, but we might as well
-				// be consistent.
-				path = path.replace(/\\/g, '/');
 				if (!path.startsWith(tmpFilePath)) {
-					Zotero.logError(path + " does not start with temp path -- not converting relative path for item " + libraryKey);
+					Zotero.logError(path + " does not start with " + tmpFilePath
+						+ " -- not converting relative path for item " + libraryKey);
 					continue;
 				}
 				path = prefix + path.substr(tmpFilePath.length + 1);
diff --git a/test/tests/attachmentsTest.js b/test/tests/attachmentsTest.js
index 6e5735327..255451809 100644
--- a/test/tests/attachmentsTest.js
+++ b/test/tests/attachmentsTest.js
@@ -177,6 +177,14 @@ describe("Zotero.Attachments", function() {
 		})
 	})
 	
+	describe("#getBaseDirectoryRelativePath()", function () {
+		it("should convert backslashes to forward slashes", function () {
+			Zotero.Prefs.set('baseAttachmentPath', "C:\\foo\\bar");
+			var path = Zotero.Attachments.getBaseDirectoryRelativePath("C:\\foo\\bar\\test\\file.txt");
+			assert.equal(path, Zotero.Attachments.BASE_PATH_PLACEHOLDER + "test/file.txt");
+		});
+	});
+	
 	describe("#getTotalFileSize", function () {
 		it("should return the size for a single-file attachment", function* () {
 			var file = getTestDataDirectory();