diff --git a/src/core/fonts.js b/src/core/fonts.js
index 964a80df2..43274086f 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -201,7 +201,7 @@ function adjustType1ToUnicode(properties, builtInEncoding) {
   for (const charCode in builtInEncoding) {
     if (properties.hasEncoding) {
       if (
-        properties.differences.length === 0 ||
+        properties.baseEncodingName ||
         properties.differences[charCode] !== undefined
       ) {
         continue; // The font dictionary has an `Encoding`/`Differences` entry.
diff --git a/test/pdfs/.gitignore b/test/pdfs/.gitignore
index a7aed6e8b..b83117441 100644
--- a/test/pdfs/.gitignore
+++ b/test/pdfs/.gitignore
@@ -399,6 +399,7 @@
 !issue4461.pdf
 !issue4573.pdf
 !issue4722.pdf
+!bug1811668_reduced.pdf
 !issue4800.pdf
 !issue9243.pdf
 !issue13147.pdf
diff --git a/test/pdfs/bug1811668_reduced.pdf b/test/pdfs/bug1811668_reduced.pdf
new file mode 100644
index 000000000..298675dbc
Binary files /dev/null and b/test/pdfs/bug1811668_reduced.pdf differ
diff --git a/test/test_manifest.json b/test/test_manifest.json
index f40e08e5d..95bfd0141 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -1006,6 +1006,12 @@
        "lastPage": 1,
        "type": "eq"
     },
+    {  "id": "bug1811668",
+       "file": "pdfs/bug1811668_reduced.pdf",
+       "md5": "87aa65d89aa0682cbe7b87152b884495",
+       "rounds": 1,
+       "type": "text"
+    },
     {  "id": "issue8092",
        "file": "pdfs/issue8092.pdf",
        "md5": "e4f3376b35fd132580246c3db1fbd738",