diff --git a/src/Base/UnitsSchema.h b/src/Base/UnitsSchema.h
index 6587d5359b..6a459bc520 100644
--- a/src/Base/UnitsSchema.h
+++ b/src/Base/UnitsSchema.h
@@ -36,7 +36,7 @@ class Quantity;
 /**
  * An individual schema object
  */
-class UnitsSchema
+class BaseExport UnitsSchema
 {
 public:
     explicit UnitsSchema(UnitsSchemaSpec spec);
diff --git a/src/Gui/PreferencePages/DlgSettingsGeneral.cpp b/src/Gui/PreferencePages/DlgSettingsGeneral.cpp
index 48755f9f50..c668f5f38b 100644
--- a/src/Gui/PreferencePages/DlgSettingsGeneral.cpp
+++ b/src/Gui/PreferencePages/DlgSettingsGeneral.cpp
@@ -749,7 +749,8 @@ void DlgSettingsGeneral::onUnitSystemIndexChanged(const int index)
     }
 
     // Enable/disable the fractional inch option depending on system
-    const auto visible = UnitsApi::isMultiUnitLength();
+    const auto schema = UnitsApi::createSchema(index);
+    const auto visible = schema->isMultiUnitLength();
     ui->comboBox_FracInch->setVisible(visible);
     ui->fractionalInchLabel->setVisible(visible);
 }