diff --git a/core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java b/core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java
index edbd2dd6226..bf061923bfa 100644
--- a/core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java
+++ b/core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java
@@ -2794,9 +2794,9 @@ public static double log(BigDecimal d0, BigDecimal d1) {
   }
 
   /** SQL {@code LOG2(number)} function applied to
-   * BigDecimal and double values. */
+   * BigDecimal values. */
   public static @Nullable Double log2(BigDecimal d0) {
-    return (d0.doubleValue() < 0.0 || d0.doubleValue() == 0.0) ? null : log(d0, 2);
+    return log2(d0.doubleValue());
   }
 
   // MOD
diff --git a/core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java b/core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java
index d9a4b5cf132..97b3e52d148 100644
--- a/core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java
+++ b/core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java
@@ -2157,7 +2157,7 @@ private static RelDataType deriveTypeMapFromEntries(SqlOperatorBinding opBinding
   @LibraryOperator(libraries = {MYSQL, SPARK})
   public static final SqlFunction LOG2 =
       SqlBasicFunction.create("LOG2",
-          ReturnTypes.DOUBLE_NULLABLE,
+          ReturnTypes.DOUBLE_FORCE_NULLABLE,
           OperandTypes.NUMERIC,
           SqlFunctionCategory.NUMERIC);
 
diff --git a/core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java b/core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java
index f8696893b04..df21ab9754d 100644
--- a/core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java
+++ b/core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java
@@ -396,6 +396,13 @@ public static SqlCall stripSeparator(SqlCall call) {
   public static final SqlReturnTypeInference DOUBLE_NULLABLE =
       DOUBLE.andThen(SqlTypeTransforms.TO_NULLABLE);
 
+  /**
+   * Type-inference strategy whereby the result type of a call is a nullable
+   * Double.
+   */
+  public static final SqlReturnTypeInference DOUBLE_FORCE_NULLABLE =
+      DOUBLE.andThen(SqlTypeTransforms.FORCE_NULLABLE);
+
   /**
    * Type-inference strategy whereby the result type of a call is a Char.
    */