diff --git a/chrome/content/zotero/xpcom/utilities_internal.js b/chrome/content/zotero/xpcom/utilities_internal.js
index 55d484259b..9f70593f05 100644
--- a/chrome/content/zotero/xpcom/utilities_internal.js
+++ b/chrome/content/zotero/xpcom/utilities_internal.js
@@ -972,7 +972,9 @@ Zotero.Utilities.Internal = {
 			for (let cslVar in map) {
 				let normalized = this._normalizeExtraKey(cslVar);
 				let existing = fieldNames.get(normalized) || [];
-				fieldNames.set(normalized, new Set([...existing, ...map[cslVar]]));
+				// Text fields are one-to-many; date fields are one-to-one
+				let additional = Array.isArray(map[cslVar]) ? map[cslVar] : [map[cslVar]];
+				fieldNames.set(normalized, new Set([...existing, ...additional]));
 			}
 		}
 		
diff --git a/test/tests/utilities_internalTest.js b/test/tests/utilities_internalTest.js
index b4db6f431b..71f2b177d0 100644
--- a/test/tests/utilities_internalTest.js
+++ b/test/tests/utilities_internalTest.js
@@ -215,6 +215,14 @@ describe("Zotero.Utilities.Internal", function () {
 			assert.equal(creators[0].name, 'Bar');
 		});
 		
+		it("should extract a CSL date field", function () {
+			var str = 'issued: 2000';
+			var { fields, extra } = Zotero.Utilities.Internal.extractExtraFields(str);
+			assert.equal(fields.size, 1);
+			assert.equal(fields.get('date'), 2000);
+			assert.strictEqual(extra, '');
+		});
+		
 		it("should extract a CSL name", function () {
 			var str = 'container-author: First || Last';
 			var { creators, extra } = Zotero.Utilities.Internal.extractExtraFields(str);
@@ -243,6 +251,15 @@ describe("Zotero.Utilities.Internal", function () {
 			assert.lengthOf(creators, 0);
 			assert.strictEqual(extra, str);
 		});
+		
+		it("should extract the citeproc-js cheater syntax", function () {
+			var issued = '{:number-of-pages:11}\n{:issued:2014}';
+			var { fields, extra } = Zotero.Utilities.Internal.extractExtraFields(issued);
+			assert.equal(fields.size, 2);
+			assert.equal(fields.get('numPages'), 11);
+			assert.equal(fields.get('date'), 2014);
+			assert.strictEqual(extra, '');
+		});
 	});
 	
 	describe("#combineExtraFields", function () {