diff --git a/src/evaluator.js b/src/evaluator.js
index f6ef31c9b..ed49f821b 100644
--- a/src/evaluator.js
+++ b/src/evaluator.js
@@ -161,7 +161,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
           translated = this.translateFont(font, xref, resources,
                                           dependency);
         } catch (e) {
-          translated = { error: e };
+          translated = { error: e instanceof Error ? e.message : e };
         }
         font.translated = translated;
 
diff --git a/src/fonts.js b/src/fonts.js
index 17d847a8d..e7cac1345 100644
--- a/src/fonts.js
+++ b/src/fonts.js
@@ -3557,6 +3557,10 @@ var Font = (function FontClosure() {
         this.glyphNameMap = properties.glyphNameMap;
       }
 
+      if (ids.length === 0) {
+        error('Valid glyph data is not found');
+      }
+
       // Converting glyphs and ids into font's cmap table
       cmap.data = createCMapTable(glyphs, ids);
       var unicodeIsEnabled = [];