1 files changed, 12 insertions, 1 deletions

diff --git a/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/DnfBuilder.java b/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/DnfBuilder.java
index dcf7611d..8e38ca6b 100644
--- a/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/DnfBuilder.java
+++ b/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/DnfBuilder.java
@@ -223,7 +223,8 @@ public final class DnfBuilder {
                         } else if (result instanceof ClausePostProcessor.ConstantResult constantResult) {
                                 switch (constantResult) {
                                 case ALWAYS_TRUE -> {
-                                        return List.of(new DnfClause(Set.of(), List.of()));
+                                        var inputVariables = getInputVariables();
+                                        return List.of(new DnfClause(inputVariables, List.of()));
                                 }
                                 case ALWAYS_FALSE -> {
                                         // Skip this clause because it can never match.
@@ -248,4 +249,14 @@ public final class DnfBuilder {
                 }
                 return Collections.unmodifiableMap(mutableParameterInfoMap);
         }
+
+        private Set<Variable> getInputVariables() {
+                var inputParameters = new LinkedHashSet<Variable>();
+                for (var parameter : parameters) {
+                        if (parameter.getDirection() == ParameterDirection.IN) {
+                                inputParameters.add(parameter.getVariable());
+                        }
+                }
+                return Collections.unmodifiableSet(inputParameters);
+        }
 }