1 files changed, 3 insertions, 2 deletions

diff --git a/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/SymbolicParameter.java b/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/SymbolicParameter.java
index e0d3ba1f..fe9cefcc 100644
--- a/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/SymbolicParameter.java
+++ b/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/SymbolicParameter.java
@@ -5,6 +5,7 @@
  */
 package tools.refinery.store.query.dnf;
 
+import tools.refinery.store.query.equality.LiteralHashCodeHelper;
 import tools.refinery.store.query.term.Parameter;
 import tools.refinery.store.query.term.ParameterDirection;
 import tools.refinery.store.query.term.Variable;
@@ -23,8 +24,8 @@ public final class SymbolicParameter extends Parameter {
                 return variable;
         }
 
-        public boolean isUnifiable() {
-                return variable.isUnifiable();
+        public int hashCodeWithSubstitution(LiteralHashCodeHelper helper) {
+                return Objects.hash(super.hashCode(), helper.getVariableHashCode(variable));
         }
 
         @Override