diff --git a/src/ifcparse/IfcFile.cpp b/src/ifcparse/IfcFile.cpp
index 7c964d3fda..bd312d51cb 100644
--- a/src/ifcparse/IfcFile.cpp
+++ b/src/ifcparse/IfcFile.cpp
@@ -46,13 +46,6 @@ namespace {
     template<typename Variant, typename T>
     constexpr bool is_type_in_variant_v = is_type_in_variant<Variant, T>::value;
 
-    struct InstanceReference {
-        int v;
-        operator int() const {
-            return v;
-        }
-    };
-
     template <typename Fn>
     void dispatch_token(int instance_id, int attribute_id, IfcParse::Token t, IfcParse::declaration* decl, Fn fn) {
         if (t.type == IfcParse::Token_BINARY) {
@@ -75,7 +68,7 @@ namespace {
         } else if (t.type == IfcParse::Token_FLOAT) {
             fn(IfcParse::TokenFunc::asFloat(t));
         } else if (t.type == IfcParse::Token_IDENTIFIER) {
-            fn(IfcParse::reference_or_simple_type{ InstanceReference{ IfcParse::TokenFunc::asIdentifier(t) } });
+            fn(IfcParse::reference_or_simple_type{ IfcParse::InstanceReference{ IfcParse::TokenFunc::asIdentifier(t), t.startPos } });
         } else if (t.type == IfcParse::Token_INT) {
             fn(IfcParse::TokenFunc::asInt(t));
         } else if (t.type == IfcParse::Token_STRING) {
diff --git a/src/ifcparse/IfcFile.h b/src/ifcparse/IfcFile.h
index a61c9f94b7..acfe6f4c89 100644
--- a/src/ifcparse/IfcFile.h
+++ b/src/ifcparse/IfcFile.h
@@ -66,7 +66,15 @@ class IFC_PARSE_API file_open_status {
     }
 };
 
-typedef boost::variant<int, IfcUtil::IfcBaseClass*> reference_or_simple_type;
+struct InstanceReference {
+    int v;
+    size_t file_offset;
+    operator int() const {
+        return v;
+    }
+};
+
+typedef boost::variant<InstanceReference, IfcUtil::IfcBaseClass*> reference_or_simple_type;
 typedef std::list<std::pair<MutableAttributeValue, boost::variant<reference_or_simple_type, std::vector<reference_or_simple_type>, std::vector<std::vector<reference_or_simple_type>>>>> unresolved_references;
 
 struct parse_context {
diff --git a/src/ifcparse/IfcParse.cpp b/src/ifcparse/IfcParse.cpp
index 2eec8ea867..021b9a1099 100644
--- a/src/ifcparse/IfcParse.cpp
+++ b/src/ifcparse/IfcParse.cpp
@@ -1423,10 +1423,10 @@ void IfcFile::initialize_(IfcParse::IfcSpfStream* s) {
         const auto& ref = p.first.name_;
         const auto& refattr = p.first.index_;
         if (auto* v = boost::get<reference_or_simple_type>(&p.second)) {
-            if (auto* name = boost::get<int>(v)) {
+            if (auto* name = boost::get<InstanceReference>(v)) {
                 entity_by_id_t::const_iterator it = byid_.find(*name);
                 if (it == byid_.end()) {
-                    Logger::Error("Instance reference #" + std::to_string(*name) + " used by instance #" + std::to_string(ref) + " at attribute index " + std::to_string(refattr) + " not found");
+                    Logger::Error("Instance reference #" + std::to_string(*name) + " used by instance #" + std::to_string(ref) + " at attribute index " + std::to_string(refattr) + " not found at offset " + std::to_string(name->file_offset));
                 } else {
                     byid_[p.first.name_]->data().storage_.set(p.first.index_, it->second);
                 }
@@ -1437,10 +1437,10 @@ void IfcFile::initialize_(IfcParse::IfcSpfStream* s) {
             aggregate_of_instance::ptr instances(new aggregate_of_instance);
             instances->reserve(v->size());
             for (const auto& vi : *v) {
-                if (auto* name = boost::get<int>(&vi)) {
+                if (auto* name = boost::get<InstanceReference>(&vi)) {
                     entity_by_id_t::const_iterator it = byid_.find(*name);
                     if (it == byid_.end()) {
-                        Logger::Error("Instance reference #" + std::to_string(*name) + " used by instance #" + std::to_string(ref) + " at attribute index " + std::to_string(refattr) + " not found");
+                        Logger::Error("Instance reference #" + std::to_string(*name) + " used by instance #" + std::to_string(ref) + " at attribute index " + std::to_string(refattr) + " not found at offset " + std::to_string(name->file_offset));
                     } else {
                         instances->push(it->second);
                     }
@@ -1454,10 +1454,10 @@ void IfcFile::initialize_(IfcParse::IfcSpfStream* s) {
             for (const auto& vi : *v) {
                 std::vector<IfcUtil::IfcBaseClass*> inner;
                 for (const auto& vii : vi) {
-                    if (auto* name = boost::get<int>(&vii)) {
+                    if (auto* name = boost::get<InstanceReference>(&vii)) {
                         entity_by_id_t::const_iterator it = byid_.find(*name);
                         if (it == byid_.end()) {
-                            Logger::Error("Instance reference #" + std::to_string(*name) + " used by instance #" + std::to_string(ref) + " at attribute index " + std::to_string(refattr) + " not found");
+                            Logger::Error("Instance reference #" + std::to_string(*name) + " used by instance #" + std::to_string(ref) + " at attribute index " + std::to_string(refattr) + " not found at offset " + std::to_string(name->file_offset));
                         } else {
                             inner.push_back(it->second);
                         }