diff --git a/core/src/main/java/org/apache/calcite/sql/type/NullOperandTypeChecker.java b/core/src/main/java/org/apache/calcite/sql/type/NotNullOperandTypeChecker.java
similarity index 92%
rename from core/src/main/java/org/apache/calcite/sql/type/NullOperandTypeChecker.java
rename to core/src/main/java/org/apache/calcite/sql/type/NotNullOperandTypeChecker.java
index 7810f8d2914f..e6deba1163bb 100644
--- a/core/src/main/java/org/apache/calcite/sql/type/NullOperandTypeChecker.java
+++ b/core/src/main/java/org/apache/calcite/sql/type/NotNullOperandTypeChecker.java
@@ -25,14 +25,14 @@
 /**
  * Parameter type-checking strategy where all operand types must not be NULL.
  */
-public class NullOperandTypeChecker extends SameOperandTypeChecker {
+public class NotNullOperandTypeChecker extends SameOperandTypeChecker {
   //~ Instance fields --------------------------------------------------------
 
   private final boolean allowCast;
 
   //~ Constructors -----------------------------------------------------------
 
-  public NullOperandTypeChecker(final int nOperands, final boolean allowCast) {
+  public NotNullOperandTypeChecker(final int nOperands, final boolean allowCast) {
     super(nOperands);
     this.allowCast = allowCast;
   }
diff --git a/core/src/main/java/org/apache/calcite/sql/type/OperandTypes.java b/core/src/main/java/org/apache/calcite/sql/type/OperandTypes.java
index efb182b8080b..18767f5a7d18 100644
--- a/core/src/main/java/org/apache/calcite/sql/type/OperandTypes.java
+++ b/core/src/main/java/org/apache/calcite/sql/type/OperandTypes.java
@@ -645,7 +645,7 @@ public static SqlOperandTypeChecker variadic(
    * Operand type-checking strategy where all types must be non-NULL value.
    */
   public static final SqlSingleOperandTypeChecker NONNULL_NONNULL =
-      new NullOperandTypeChecker(2, false);
+      new NotNullOperandTypeChecker(2, false);
 
   /**
    * Operand type-checking strategy type must be a boolean non-NULL literal.