diff --git a/reactor/Core/src/jetbrains/mps/unification/TermGraphUnifier.kt b/reactor/Core/src/jetbrains/mps/unification/TermGraphUnifier.kt
index 28ba2516..140927ec 100644
--- a/reactor/Core/src/jetbrains/mps/unification/TermGraphUnifier.kt
+++ b/reactor/Core/src/jetbrains/mps/unification/TermGraphUnifier.kt
@@ -18,6 +18,7 @@ package jetbrains.mps.unification
 
 import gnu.trove.list.array.TIntArrayList
 import gnu.trove.map.hash.TIntObjectHashMap
+import jetbrains.mps.logic.reactor.logical.Logical
 import jetbrains.mps.unification.Substitution.FailureCause.CYCLE_DETECTED
 import jetbrains.mps.unification.Substitution.FailureCause.SYMBOL_CLASH
 import jetbrains.mps.unification.Term.Kind.*
@@ -294,13 +295,15 @@ class TermGraphUnifier {
         return wrapper.unwrap(origin[t])
     }
 
-    private fun idSymbol(symbol: Any): Any {
-        return if (symbol is String)  symbol.intern() else symbol
-    }
-    
+    private fun idSymbol(symbol: Any): Any =
+        when (symbol) {
+            is String       -> symbol.intern()
+            is Logical<*>   -> symbol.findRoot()
+            else            -> symbol
+        }
+
     private fun Any?.eq (that: Any?): Boolean {
         return if (this == null) that == null else this.equals(that)
     }
 
-
 }
\ No newline at end of file
diff --git a/reactor/Test/test/jetbrains/mps/unification/test/SolverTests.java b/reactor/Test/test/jetbrains/mps/unification/test/SolverTests.java
index eed9f766..e273c0a6 100644
--- a/reactor/Test/test/jetbrains/mps/unification/test/SolverTests.java
+++ b/reactor/Test/test/jetbrains/mps/unification/test/SolverTests.java
@@ -16,6 +16,9 @@
 
 package jetbrains.mps.unification.test;
 
+import jetbrains.mps.logic.reactor.core.LogicalImpl;
+import jetbrains.mps.logic.reactor.logical.MetaLogical;
+import jetbrains.mps.unification.Substitution;
 import jetbrains.mps.unification.Term;
 import jetbrains.mps.unification.TermWrapper;
 import org.jetbrains.annotations.NotNull;
@@ -543,4 +546,44 @@ public class SolverTests {
     }
 
 
+    @Test
+    public void joinedLogicals() throws Exception {
+        MetaLogical<Term> X = new MetaLogical<>("X", Term.class);
+        MetaLogical<Term> Y = new MetaLogical<>("Y", Term.class);
+        MetaLogical<Term> Z = new MetaLogical<>("Z", Term.class);
+        LogicalImpl<Term> xLogical = new LogicalImpl<>(X);
+        LogicalImpl<Term> yLogical = new LogicalImpl<>(Y);
+        LogicalImpl<Term> zLogical = new LogicalImpl<>(Z);
+
+        Term left = term("foo", term("bar", logicalVar(yLogical)), logicalVar(zLogical));
+        Term right = term("foo", term("bar", logicalVar(xLogical)), logicalVar(zLogical));
+        
+        assertUnifiesWithBindings(left, right,
+                new Substitution.Binding(logicalVar(xLogical), logicalVar(yLogical)));
+
+        xLogical.union(yLogical);
+
+        assertUnifiesWithBindings(left, right);
+    }
+
+    @Test
+    public void joinedLogicals_cycle() throws Exception {
+        MetaLogical<Term> X = new MetaLogical<>("X", Term.class);
+        MetaLogical<Term> Y = new MetaLogical<>("Y", Term.class);
+        MetaLogical<Term> Z = new MetaLogical<>("Z", Term.class);
+        LogicalImpl<Term> xLogical = new LogicalImpl<>(X);
+        LogicalImpl<Term> yLogical = new LogicalImpl<>(Y);
+        LogicalImpl<Term> zLogical = new LogicalImpl<>(Z);
+
+        Term left = logicalVar(yLogical);
+        Term right = term("foo", term("bar", logicalVar(xLogical)), logicalVar(zLogical));
+
+        assertUnifiesWithBindings(left, right,
+                new Substitution.Binding(left, right));
+
+        xLogical.union(yLogical);
+
+        assertUnificationFails(left, right,
+                CYCLE_DETECTED);
+    }
 }