diff --git a/src/libcalamaresui/utils/CalamaresUtilsGui.cpp b/src/libcalamaresui/utils/CalamaresUtilsGui.cpp
index bd15d7a68..680673a22 100644
--- a/src/libcalamaresui/utils/CalamaresUtilsGui.cpp
+++ b/src/libcalamaresui/utils/CalamaresUtilsGui.cpp
@@ -207,6 +207,10 @@ unmarginLayout( QLayout* layout )
 int
 defaultFontSize()
 {
+    if ( s_defaultFontSize <= 0 )
+    {
+        s_defaultFontSize = QFont().pointSize();
+    }
     return s_defaultFontSize;
 }