diff --git a/src/core/fonts.js b/src/core/fonts.js
index 24ed0139c..9bab29cef 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -2955,10 +2955,7 @@ class Font {
         // Always prefer the BaseEncoding/Differences arrays, when they exist
         // (fixes issue13433.pdf).
         forcePostTable = true;
-      } else {
-        // When there is only a (1, 0) cmap table, the char code is a single
-        // byte and it is used directly as the char code.
-
+      } else if (cmapPlatformId === 3 && cmapEncodingId === 0) {
         // When a (3, 0) cmap table is present, it is used instead but the
         // spec has special rules for char codes in the range of 0xF000 to
         // 0xF0FF and it says the (3, 0) table should map the values from
@@ -2969,15 +2966,17 @@ class Font {
         // cmap.
         for (const mapping of cmapMappings) {
           let charCode = mapping.charCode;
-          if (
-            cmapPlatformId === 3 &&
-            charCode >= 0xf000 &&
-            charCode <= 0xf0ff
-          ) {
+          if (charCode >= 0xf000 && charCode <= 0xf0ff) {
             charCode &= 0xff;
           }
           charCodeToGlyphId[charCode] = mapping.glyphId;
         }
+      } else {
+        // When there is only a (1, 0) cmap table, the char code is a single
+        // byte and it is used directly as the char code.
+        for (const mapping of cmapMappings) {
+          charCodeToGlyphId[mapping.charCode] = mapping.glyphId;
+        }
       }
 
       // Last, try to map any missing charcodes using the post table.
diff --git a/test/pdfs/.gitignore b/test/pdfs/.gitignore
index 0fcd81388..87a32129f 100644
--- a/test/pdfs/.gitignore
+++ b/test/pdfs/.gitignore
@@ -636,3 +636,4 @@
 !bug1868759.pdf
 !issue17730.pdf
 !bug1883609.pdf
+!issue17808.pdf
diff --git a/test/pdfs/issue17808.pdf b/test/pdfs/issue17808.pdf
new file mode 100755
index 000000000..65d89961c
Binary files /dev/null and b/test/pdfs/issue17808.pdf differ
diff --git a/test/test_manifest.json b/test/test_manifest.json
index 65168819f..8927ba30e 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -9794,5 +9794,12 @@
     "rounds": 1,
     "link": true,
     "type": "other"
+  },
+  {
+    "id": "issue17808",
+    "file": "pdfs/issue17808.pdf",
+    "md5": "dd66194bdaa0f62bc96c760384f2e098",
+    "rounds": 1,
+    "type": "eq"
   }
 ]