diff --git a/content/dateparser.ts b/content/dateparser.ts
index 5446d98388..83785c2003 100644
--- a/content/dateparser.ts
+++ b/content/dateparser.ts
@@ -397,8 +397,11 @@ export function isEDTF(value: string, minuteLevelPrecision = false): boolean {
 }
 
 export function strToISO(str: string): string {
-  let date = parse(str)
-  if (date.type === 'interval') date = date.from
+  return dateToISO(parse(str))
+}
+
+export function dateToISO(date: ParsedDate): string {
+  if (date.type === 'interval') return `${dateToISO(date.from)}/${dateToISO(date.to)}`
 
   if (typeof date.year !== 'number') return ''
 
diff --git a/translators/bibtex/bibtex.ts b/translators/bibtex/bibtex.ts
index 356070ba05..c896531d3b 100644
--- a/translators/bibtex/bibtex.ts
+++ b/translators/bibtex/bibtex.ts
@@ -7,7 +7,7 @@ import { validItem } from '../../content/ajv'
 import { valid, label } from '../../gen/items/items'
 import { wordsToNumbers } from 'words-to-numbers'
 
-import { parse as parseDate, strToISO as strToISODate } from '../../content/dateparser'
+import { parse as parseDate, strToISO as strToISODate, dateToISO } from '../../content/dateparser'
 
 import { parseBuffer as parsePList } from 'bplist-parser'
 
@@ -387,7 +387,7 @@ export function generateBibTeX(translation: Translation): void {
         break
 
       case 'interval':
-        ref.add({ name: 'year', value: item.date })
+        ref.add({ name: 'year', value: dateToISO(ref.date) })
         break
 
       case 'date':