diff --git a/src/core/type1_parser.js b/src/core/type1_parser.js
index e43debfb1..ca5c78bba 100644
--- a/src/core/type1_parser.js
+++ b/src/core/type1_parser.js
@@ -654,9 +654,14 @@ class Type1Parser {
         case "BlueFuzz":
         case "BlueScale":
         case "LanguageGroup":
-        case "ExpansionFactor":
           program.properties.privateData[token] = this.readNumber();
           break;
+        case "ExpansionFactor":
+          // Firefox doesn't render correctly a font with a null factor on
+          // Windows (see issue 15289), hence we just reset it to its default
+          // value (0.06).
+          program.properties.privateData[token] = this.readNumber() || 0.06;
+          break;
         case "ForceBold":
           program.properties.privateData[token] = this.readBoolean();
           break;