diff -ur calibre-3.15.0/src/calibre/headless/fontconfig_database.cpp calibre-3.15.0-fixed/src/calibre/headless/fontconfig_database.cpp
--- calibre-3.15.0/src/calibre/headless/fontconfig_database.cpp	2018-01-05 07:41:54.000000000 +0200
+++ calibre-3.15.0-fixed/src/calibre/headless/fontconfig_database.cpp	2018-07-04 04:30:27.367199761 +0300
@@ -284,14 +284,27 @@
     "", // Hatran
     "", // Multani
     "", // OldHungarian
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 11, 0))
+    "", // SignWriting
+    "", // Script_Adlam
+    "", // Script_Bhaiksuki
+    "", // Script_Marchen
+    "", // Script_Newa
+    "", // Script_Osage
+    "", // Script_Tangut
+    "", // Script_MasaramGondi
+    "", // Script_Nushu
+    "", // Script_Soyombo
+    "", // Script_ZanabazarSquare
+#else
     ""  // SignWriting
+#endif // Qt >= 5.11.0
 #else
     "hoc"  // WarangCiti
 #endif  // Qt >= 5.6.0
 #else
     "doi" // Takri
 #endif // Qt >= 5.5.0
-
 };
 Q_STATIC_ASSERT(sizeof specialLanguages / sizeof *specialLanguages == QChar::ScriptCount);