diff --git a/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQConfig.hpp b/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQConfig.hpp
index 7efd9a6b2..9b63a3c27 100644
--- a/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQConfig.hpp
+++ b/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQConfig.hpp
@@ -32,6 +32,7 @@
 #include <opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQParams.hpp>
 #include <opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQFunctionTable.hpp>
 #include <opm/parser/eclipse/EclipseState/Util/OrderedMap.hpp>
+#include <opm/parser/eclipse/EclipseState/Util/IOrderSet.hpp>
 
 
 namespace Opm {
@@ -111,6 +112,7 @@ namespace Opm {
         std::unordered_map<std::string, UDQAssign> m_assignments;
         std::unordered_map<std::string, std::string> units;
 
+        IOrderSet<std::string> define_order;
         OrderedMap<std::string, UDQIndex> input_index;
         std::map<UDQVarType, std::size_t> type_count;
     };
diff --git a/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQConfig.cpp b/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQConfig.cpp
index a7d5674f3..f9e766fdb 100644
--- a/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQConfig.cpp
+++ b/src/opm/parser/eclipse/EclipseState/Schedule/UDQ/UDQConfig.cpp
@@ -92,6 +92,7 @@ namespace Opm {
             this->m_definitions.erase( defined_iter );
 
         this->m_definitions.insert( std::make_pair(quantity, UDQDefine(this->udq_params, quantity, expression)));
+        this->define_order.insert(quantity);
     }
 
 
@@ -146,25 +147,20 @@ namespace Opm {
 
     std::vector<UDQDefine> UDQConfig::definitions() const {
         std::vector<UDQDefine> ret;
-        for (const auto& index_pair : this->input_index) {
-            if (index_pair.second.action == UDQAction::DEFINE) {
-                const std::string& key = index_pair.first;
-                ret.push_back(this->m_definitions.at(key));
-            }
-        }
+
+        for (const auto& key : this->define_order)
+            ret.push_back(this->m_definitions.at(key));
+
         return ret;
     }
 
 
     std::vector<UDQDefine> UDQConfig::definitions(UDQVarType var_type) const {
         std::vector<UDQDefine> filtered_defines;
-        for (const auto& index_pair : this->input_index) {
-            if (index_pair.second.action == UDQAction::DEFINE) {
-                const std::string& key = index_pair.first;
-                const auto& udq_define = this->m_definitions.at(key);
-                if (udq_define.var_type() == var_type)
-                    filtered_defines.push_back(udq_define);
-            }
+        for (const auto& key : this->define_order) {
+            const auto& udq_define = this->m_definitions.at(key);
+            if (udq_define.var_type() == var_type)
+                filtered_defines.push_back(udq_define);
         }
         return filtered_defines;
     }
diff --git a/tests/parser/UDQTests.cpp b/tests/parser/UDQTests.cpp
index 105c2ce12..acf8a33ad 100644
--- a/tests/parser/UDQTests.cpp
+++ b/tests/parser/UDQTests.cpp
@@ -1749,6 +1749,25 @@ UDQ
 }
 
 
+BOOST_AUTO_TEST_CASE(UDQ_DEFINE_ORDER) {
+    std::string deck_string = R"(
+SCHEDULE
+UDQ
+ASSIGN FU_PAR1 1.0 /
+ASSIGN FU_PAR2 0.0 /
+DEFINE FU_PAR3 FMWPR /
+DEFINE FU_PAR2 FU_PAR3 /
+/
+)";
+    auto schedule = make_schedule(deck_string);
+    const auto& udq = schedule.getUDQConfig(0);
+    SummaryState st(std::chrono::system_clock::now());
+    st.update("FMWPR", 100);
+    udq.eval(st);
+
+    BOOST_CHECK_EQUAL(st.get("FU_PAR2"), 100);
+}
+
 
 BOOST_AUTO_TEST_CASE(UDQ_UADD_PARSER2) {
     std::string deck_string = R"(
@@ -1798,5 +1817,18 @@ DEFINE FU_PAR24 FU_PAR24 UADD (FU_PAR14 + FU_PAR15) /
 DEFINE WUGASRA  750000 - WGLIR '*' /
 /
 )";
-    BOOST_CHECK_NO_THROW( make_schedule(deck_string) );
+    auto schedule = make_schedule(deck_string);
+    const auto& udq = schedule.getUDQConfig(0);
+    SummaryState st(std::chrono::system_clock::now());
+    st.update("FMWPR", 100);
+    st.update("FMWIN", 100);
+    st.update("FMWPA", 100);
+    st.update("FMWIA", 100);
+    st.update("FOPR", 100);
+    st.update_well_var("W1", "WGLIR", 1);
+    st.update_well_var("W2", "WGLIR", 2);
+    st.update_well_var("W3", "WGLIR", 3);
+
+    // The current testcase has some ordering & defined / undefined issues which
+    // are not yet solved; therefor no udq.eval() here.
 }