Do not force custom fontconfig configuration.
--- a/Telegram/lib_ui/fonts/fonts.qrc
+++ b/Telegram/lib_ui/fonts/fonts.qrc
@@ -1,10 +1,4 @@
 <RCC>
   <qresource prefix="/gui/fonts">
-    <file>DAOpenSansRegular.ttf</file>
-    <file>DAOpenSansRegularItalic.ttf</file>
-    <file>DAOpenSansBold.ttf</file>
-    <file>DAOpenSansBoldItalic.ttf</file>
-    <file>DAOpenSansSemibold.ttf</file>
-    <file>DAOpenSansSemiboldItalic.ttf</file>
   </qresource>
 </RCC>
--- a/Telegram/lib_ui/ui/style/style_core_font.cpp
+++ b/Telegram/lib_ui/ui/style/style_core_font.cpp
@@ -94,12 +94,12 @@
 	FontTypesCount,
 };
 QString FontTypeNames[FontTypesCount] = {
-	"DAOpenSansRegular",
-	"DAOpenSansRegularItalic",
-	"DAOpenSansBold",
-	"DAOpenSansBoldItalic",
-	"DAOpenSansSemibold",
-	"DAOpenSansSemiboldItalic",
+	"Open Sans",
+	"Open Sans",
+	"Open Sans",
+	"Open Sans",
+	"Open Sans Semibold",
+	"Open Sans Semibold",
 };
 int32 FontTypeFlags[FontTypesCount] = {
 	0,
@@ -135,7 +135,7 @@
 	for (auto i = 0; i != FontTypesCount; ++i) {
 		const auto name = FontTypeNames[i];
 		const auto flags = FontTypeFlags[i];
-		areGood[i] = LoadCustomFont(":/gui/fonts/" + name + ".ttf", name, flags);
+		areGood[i] = ValidateFont(name, flags);
 		Overrides[i] = name;
 #ifdef Q_OS_WIN
 		// Attempt to workaround a strange font bug with Open Sans Semibold not loading.
--- a/Telegram/SourceFiles/platform/linux/specific_linux.cpp.orig	2020-01-17 22:34:25.882017929 +0100
+++ b/Telegram/SourceFiles/platform/linux/specific_linux.cpp	2020-01-17 22:34:56.362548378 +0100
@@ -82,8 +82,6 @@ void FallbackFontConfig() {
 			return;
 		}
 	}
-
-	QFile(":/fc/fc-custom.conf").copy(custom);
 #endif // !DESKTOP_APP_USE_PACKAGED
 }
 
--- a/Telegram/lib_ui/qt_conf/linux.qrc.orig	2020-01-17 22:38:50.902630063 +0100
+++ b/Telegram/lib_ui/qt_conf/linux.qrc	2020-01-17 22:39:09.298950213 +0100
@@ -3,6 +3,5 @@
     <file alias="qt.conf">qt_linux.conf</file>
   </qresource>
   <qresource prefix="/fc">
-    <file>fc-custom.conf</file>
   </qresource>
 </RCC>