diff --git a/src/ifcgeom/GeometrySerializer.h b/src/ifcgeom/GeometrySerializer.h
index 7cedf8cf97..75cf038e40 100644
--- a/src/ifcgeom/GeometrySerializer.h
+++ b/src/ifcgeom/GeometrySerializer.h
@@ -76,11 +76,16 @@ inline namespace settings {
 			" and any other value means that 6 or 7 decimals are used.";
 		static constexpr int defaultvalue = 15;
 	};
+
+	struct BaseUri : public SettingBase<BaseUri, std::string> {
+		static constexpr const char* const name = "base-uri";
+		static constexpr const char* const description = "Base URI for products to be used in RDF-based serializations.";
+	};
 }
 
 class SerializerSettings : public SettingsContainer <
 	// @todo should we use tuple_cat here to unify the settings into a single class?
-	std::tuple<UseElementNames, UseElementGuids, UseElementStepIds, UseElementTypes, UseYUp, WriteGltfEcef, FloatingPointDigits>
+	std::tuple<UseElementNames, UseElementGuids, UseElementStepIds, UseElementTypes, UseYUp, WriteGltfEcef, FloatingPointDigits, BaseUri>
 >
 {};
 
diff --git a/src/serializers/TtlWktSerializer.cpp b/src/serializers/TtlWktSerializer.cpp
index 7fd8962c01..9920489860 100644
--- a/src/serializers/TtlWktSerializer.cpp
+++ b/src/serializers/TtlWktSerializer.cpp
@@ -223,9 +223,14 @@ bool TtlWktSerializer::ready()
 
 void TtlWktSerializer::writeHeader()
 {
+    using namespace ifcopenshell::geometry::settings;
     filename_.stream << "# File generated by IfcOpenShell " << IFCOPENSHELL_VERSION << "\n";
     filename_.stream << "@prefix geo: <http://www.opengis.net/ont/geosparql#> .\n";
-    filename_.stream << "@prefix ex: <http://example.org/> .\n";
+    if (settings_.get<BaseUri>().has()) {
+        filename_.stream << "@prefix base: <" << settings_.get<BaseUri>().get() << "> .\n";
+    } else {
+        filename_.stream << "@prefix base: <http://example.org/> .\n";
+    }
     filename_.stream << "@prefix dcterms: <http://purl.org/dc/terms/> .\n";
     filename_.stream << "@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .\n\n\n";
 }
@@ -233,19 +238,19 @@ void TtlWktSerializer::writeHeader()
 void TtlWktSerializer::write(const IfcGeom::TriangulationElement* o)
 {
     auto ttl_object_id = [&]() {
-        return boost::replace_all_copy(object_id(o), "-", "_");
+        return boost::replace_all_copy(boost::replace_all_copy(object_id(o), "-", "_"), "$", "%24");
     };
 
-    filename_.stream << "ex:" << ttl_object_id() << " a geo:Feature ;\n";
+    filename_.stream << "base:" << ttl_object_id() << " a geo:Feature ;\n";
     filename_.stream << "    dcterms:identifier " << escape_for_turtle(
         IfcUtil::convert_utf8_to_utf32(o->guid())) << " ;\n";
     filename_.stream << "    rdfs:label " << escape_for_turtle(
         IfcUtil::convert_utf8_to_utf32(o->name())
     ) << " ;\n";
-    filename_.stream << "    geo:hasGeometry ex:" << ttl_object_id() << "_geometry .\n\n";
+    filename_.stream << "    geo:hasGeometry base:" << ttl_object_id() << "_geometry .\n\n";
 
     if (!o->geometry().polyhedral_faces_with_holes().empty()) {
-        filename_.stream << "ex:" << ttl_object_id() << "_geometry a geo:Geometry ;\n";
+        filename_.stream << "base:" << ttl_object_id() << "_geometry a geo:Geometry ;\n";
         filename_.stream << "    geo:asWKT " << escape_for_turtle(
             IfcUtil::convert_utf8_to_utf32(
                 capture_output(
@@ -275,8 +280,8 @@ void TtlWktSerializer::write(const IfcGeom::TriangulationElement* o)
         }
 
         if (lowest_face) {
-            filename_.stream << "ex:" << ttl_object_id() << " geo:hasGeometry ex:" << ttl_object_id() << "_footprint_geometry .\n\n";
-            filename_.stream << "ex:" << ttl_object_id() << "_footprint_geometry a geo:Geometry ;\n";
+            filename_.stream << "base:" << ttl_object_id() << " geo:hasGeometry base:" << ttl_object_id() << "_footprint_geometry .\n\n";
+            filename_.stream << "base:" << ttl_object_id() << "_footprint_geometry a geo:Geometry ;\n";
             filename_.stream << "    geo:asWKT " << escape_for_turtle(
                 IfcUtil::convert_utf8_to_utf32(
                     capture_output(
@@ -290,7 +295,7 @@ void TtlWktSerializer::write(const IfcGeom::TriangulationElement* o)
             ) << "^^geo:wktLiteral .\n\n";
         }
     } else {
-        filename_.stream << "ex:" << ttl_object_id() << "_geometry a geo:Geometry ;\n";
+        filename_.stream << "base:" << ttl_object_id() << "_geometry a geo:Geometry ;\n";
         bool force_2d = true;
         double z_value;
         for (size_t i = 2; i < o->geometry().verts().size(); i += 3) {