diff --git a/src/core/fonts.js b/src/core/fonts.js
index 0146151e6..3562a7dc9 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -2690,6 +2690,7 @@ var Font = (function FontClosure() {
            fontCharCode <= 0x1f || // Control chars
            fontCharCode === 0x7F || // Control char
            fontCharCode === 0xAD || // Soft hyphen
+           fontCharCode === 0xA0 || // Non breaking space
            (fontCharCode >= 0x80 && fontCharCode <= 0x9F) || // Control chars
            // Prevent drawing characters in the specials unicode block.
            (fontCharCode >= 0xFFF0 && fontCharCode <= 0xFFFF) ||
@@ -4708,6 +4709,8 @@ function type1FontGlyphMapping(properties, builtInEncoding, glyphNames) {
       glyphId = glyphNames.indexOf(baseEncoding[charCode]);
       if (glyphId >= 0) {
         charCodeToGlyphId[charCode] = glyphId;
+      } else {
+        charCodeToGlyphId[charCode] = 0; // notdef
       }
     }
   } else if (!!(properties.flags & FontFlags.Symbolic)) {
@@ -4724,6 +4727,8 @@ function type1FontGlyphMapping(properties, builtInEncoding, glyphNames) {
       glyphId = glyphNames.indexOf(baseEncoding[charCode]);
       if (glyphId >= 0) {
         charCodeToGlyphId[charCode] = glyphId;
+      } else {
+        charCodeToGlyphId[charCode] = 0; // notdef
       }
     }
   }
@@ -4736,6 +4741,8 @@ function type1FontGlyphMapping(properties, builtInEncoding, glyphNames) {
       glyphId = glyphNames.indexOf(glyphName);
       if (glyphId >= 0) {
         charCodeToGlyphId[charCode] = glyphId;
+      } else {
+        charCodeToGlyphId[charCode] = 0; // notdef
       }
     }
   }
diff --git a/test/pdfs/issue5138.pdf b/test/pdfs/issue5138.pdf
new file mode 100644
index 000000000..715ddf31f
Binary files /dev/null and b/test/pdfs/issue5138.pdf differ
diff --git a/test/test_manifest.json b/test/test_manifest.json
index ed4bec3a6..05a69ce4a 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -615,6 +615,14 @@
        "type": "eq",
        "about": "Glyph accent drawn as curves."
     },
+    {  "id": "issue5138",
+       "file": "pdfs/issue5138.pdf",
+       "md5": "9931686d7dee0df62640fbf58bed3323",
+       "link": false,
+       "rounds": 1,
+       "type": "eq",
+       "about": "Glyph that gets mapped to unicode non-breaking-space."
+    },
     {  "id": "simpletype3font",
        "file": "pdfs/simpletype3font.pdf",
        "md5": "b374c7543920840c61999e9e86939f99",