diff --git a/core/src/main/java/org/apache/calcite/rex/RexCall.java b/core/src/main/java/org/apache/calcite/rex/RexCall.java
index 98d352e31d5..40b38d64684 100644
--- a/core/src/main/java/org/apache/calcite/rex/RexCall.java
+++ b/core/src/main/java/org/apache/calcite/rex/RexCall.java
@@ -57,11 +57,18 @@ public class RexCall extends RexNode {
   public final ImmutableList<RexNode> operands;
   public final RelDataType type;
 
+  /**
+   * Simple binary operators are those operators which expects operands from the same Domain.
+   *
+   * Example: simple comparisions (=,&lt;)
+   * Note: it doesn't contain IN because that is defined on D x D^n
+   */
   private static final Set<SqlKind> SIMPLE_BINARY_OPS;
 
   static {
     EnumSet<SqlKind> kinds = EnumSet.of(SqlKind.PLUS, SqlKind.MINUS, SqlKind.TIMES, SqlKind.DIVIDE);
     kinds.addAll(SqlKind.COMPARISON);
+    kinds.remove(SqlKind.IN);
     SIMPLE_BINARY_OPS = Sets.immutableEnumSet(kinds);
   }
 
@@ -111,7 +118,7 @@ protected final StringBuilder appendOperands(StringBuilder sb) {
           && operand.getType().getSqlTypeName() == SqlTypeName.BOOLEAN) {
         includeType = RexDigestIncludeType.NO_TYPE;
       }
-      if (SIMPLE_BINARY_OPS.contains(getKind())) {
+      if (SIMPLE_BINARY_OPS.contains(getKind()) && operands.size() == 2) {
         RexNode otherArg = operands.get(1 - i);
         if ((!(otherArg instanceof RexLiteral)
             || ((RexLiteral) otherArg).digestIncludesType() == RexDigestIncludeType.NO_TYPE)
diff --git a/core/src/test/java/org/apache/calcite/test/RexProgramTest.java b/core/src/test/java/org/apache/calcite/test/RexProgramTest.java
index 23045225071..9e4ebf924c6 100644
--- a/core/src/test/java/org/apache/calcite/test/RexProgramTest.java
+++ b/core/src/test/java/org/apache/calcite/test/RexProgramTest.java
@@ -2546,6 +2546,14 @@ private void checkIs(RexNode e, boolean expected) {
   private Comparable eval(RexNode e) {
     return RexInterpreter.evaluate(e, ImmutableMap.of());
   }
-}
 
+  /** Unit test for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-2842">[CALCITE-2842]
+   * Computing digest of IN expressions leads to Exceptions</a>. */
+  @Test public void testInDigest() {
+    RexNode e = in(vInt(), literal(1), literal(2));
+    assertThat(e.toString(), is("IN(?0.int0, 1, 2)"));
+  }
+
+}
 // End RexProgramTest.java