diff --git a/chrome/content/zotero/xpcom/reader.js b/chrome/content/zotero/xpcom/reader.js
index 7013f01e62..4814912e47 100644
--- a/chrome/content/zotero/xpcom/reader.js
+++ b/chrome/content/zotero/xpcom/reader.js
@@ -146,6 +146,7 @@ class ReaderInstance {
 		buf = new Uint8Array(buf).buffer;
 		let annotationItems = this._item.getAnnotations();
 		let annotations = (await Promise.all(annotationItems.map(x => this._getAnnotation(x)))).filter(x => x);
+		let resourceBaseURI = `zotero://attachment/${Zotero.API.getLibraryPrefix(this._item.libraryID)}/items/${this._item.key}/`;
 
 		// TODO: Remove after some time
 		// Migrate Mendeley colors to Zotero PDF reader colors
@@ -189,6 +190,7 @@ class ReaderInstance {
 				type: this._type,
 				buf: new Uint8Array(buf),
 				annotations,
+				resourceBaseURI,
 				primaryViewState: state,
 				secondaryViewState: secondViewState,
 				location,
diff --git a/components/zotero-protocol-handler.js b/components/zotero-protocol-handler.js
index 9366fb4551..8ad9fc1e0d 100644
--- a/components/zotero-protocol-handler.js
+++ b/components/zotero-protocol-handler.js
@@ -57,14 +57,18 @@ function ZoteroProtocolHandler() {
 	
 	
 	/**
-	 * zotero://attachment/library/[itemKey]
-	 * zotero://attachment/groups/[groupID]/[itemKey]
+	 * zotero://attachment/library/items/[itemKey]
+	 * zotero://attachment/groups/[groupID]/items/[itemKey]
+	 *
+	 * And for snapshot attachments only:
+	 * zotero://attachment/library/items/[itemKey]/[resourcePath]
+	 * zotero://attachment/groups/[groupID]/items/[itemKey]/[resourcePath]
 	 */
 	var AttachmentExtension = {
 		loadAsChrome: false,
 		
-		newChannel: function (uri) {
-			return new AsyncChannel(uri, function* () {
+		newChannel: function (uri, loadInfo) {
+			return new AsyncChannel(uri, loadInfo, function* () {
 				try {
 					var uriPath = uri.pathQueryRef;
 					if (!uriPath) {
@@ -100,6 +104,26 @@ function ZoteroProtocolHandler() {
 						return this._errorChannel(`${path} not found`);
 					}
 					
+					var resourcePathParts = uriPath.split('/')
+						.slice(params.groupID !== undefined ? 4 : 3)
+						.filter(Boolean);
+					if (resourcePathParts.length) {
+						if (!item.isSnapshotAttachment()) {
+							return this._errorChannel(`Item for ${uriPath} is not a snapshot attachment -- cannot access resources`);
+						}
+						
+						try {
+							path = PathUtils.join(PathUtils.parent(path), ...resourcePathParts);
+						}
+						catch (e) {
+							Zotero.logError(e);
+							return this._errorChannel(`Resource ${resourcePathParts.join('/')} not found`);
+						}
+						if (!(yield IOUtils.exists(path))) {
+							return this._errorChannel(`Resource ${resourcePathParts.join('/')} not found`);
+						}
+					}
+					
 					// Set originalURI so that it seems like we're serving from zotero:// protocol.
 					// This is necessary to allow url() links to work from within CSS files.
 					// Otherwise they try to link to files on the file:// protocol, which isn't allowed.