diff --git a/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala b/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala
index 02a76f69f0..9322149e46 100644
--- a/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala
+++ b/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala
@@ -105,6 +105,7 @@ object QueryPlanSerde extends Logging with CometExprShim {
     classOf[Log] -> CometLog,
     classOf[Log2] -> CometLog2,
     classOf[Log10] -> CometLog10,
+    classOf[Logarithm] -> CometLogarithm,
     classOf[Multiply] -> CometMultiply,
     classOf[Pow] -> CometScalarFunction("pow"),
     classOf[Rand] -> CometRand,
diff --git a/spark/src/main/scala/org/apache/comet/serde/math.scala b/spark/src/main/scala/org/apache/comet/serde/math.scala
index 5a0393142a..b258ca6fae 100644
--- a/spark/src/main/scala/org/apache/comet/serde/math.scala
+++ b/spark/src/main/scala/org/apache/comet/serde/math.scala
@@ -19,7 +19,7 @@
 
 package org.apache.comet.serde
 
-import org.apache.spark.sql.catalyst.expressions.{Abs, Atan2, Attribute, Ceil, CheckOverflow, Expression, Floor, Hex, If, LessThanOrEqual, Literal, Log, Log10, Log2, Tan, Unhex}
+import org.apache.spark.sql.catalyst.expressions.{Abs, Atan2, Attribute, Ceil, CheckOverflow, Expression, Floor, Hex, If, LessThanOrEqual, Literal, Log, Log10, Log2, Logarithm, Tan, Unhex}
 import org.apache.spark.sql.types.{DecimalType, NumericType}
 
 import org.apache.comet.CometSparkSessionExtensions.withInfo
@@ -138,6 +138,20 @@ object CometLog2 extends CometExpressionSerde[Log2] with MathExprBase {
   }
 }
 
+object CometLogarithm extends CometExpressionSerde[Logarithm] with MathExprBase {
+  override def convert(
+      expr: Logarithm,
+      inputs: Seq[Attribute],
+      binding: Boolean): Option[ExprOuterClass.Expr] = {
+    // Spark's Logarithm(left=base, right=value) returns null when result is NaN,
+    // which happens when base <= 0 or value <= 0. Apply nullIfNegative to both.
+    val leftExpr = exprToProtoInternal(nullIfNegative(expr.left), inputs, binding)
+    val rightExpr = exprToProtoInternal(nullIfNegative(expr.right), inputs, binding)
+    val optExpr = scalarFunctionExprToProto("log", leftExpr, rightExpr)
+    optExprWithInfo(optExpr, expr, expr.left, expr.right)
+  }
+}
+
 object CometHex extends CometExpressionSerde[Hex] with MathExprBase {
   override def convert(
       expr: Hex,
diff --git a/spark/src/test/resources/sql-tests/expressions/math/tan.sql b/spark/src/test/resources/sql-tests/expressions/math/tan.sql
index 21bd44f907..9496844804 100644
--- a/spark/src/test/resources/sql-tests/expressions/math/tan.sql
+++ b/spark/src/test/resources/sql-tests/expressions/math/tan.sql
@@ -16,6 +16,7 @@
 -- under the License.
 
 -- ConfigMatrix: parquet.enable.dictionary=false,true
+-- Config: spark.comet.expression.Tan.allowIncompatible=true
 
 statement
 CREATE TABLE test_tan(d double) USING parquet
diff --git a/spark/src/test/scala/org/apache/comet/CometSqlFileTestSuite.scala b/spark/src/test/scala/org/apache/comet/CometSqlFileTestSuite.scala
index 020759a7a6..5a0b34e056 100644
--- a/spark/src/test/scala/org/apache/comet/CometSqlFileTestSuite.scala
+++ b/spark/src/test/scala/org/apache/comet/CometSqlFileTestSuite.scala
@@ -102,7 +102,7 @@ class CometSqlFileTestSuite extends CometTestBase with AdaptiveSparkPlanHelper {
                   case SparkAnswerOnly =>
                     checkSparkAnswer(sql)
                   case WithTolerance(tol) =>
-                    checkSparkAnswerWithTolerance(sql, tol)
+                    checkSparkAnswerAndOperatorWithTolerance(sql, tol)
                   case ExpectFallback(reason) =>
                     checkSparkAnswerAndFallbackReason(sql, reason)
                   case Ignore(reason) =>
diff --git a/spark/src/test/scala/org/apache/spark/sql/CometTestBase.scala b/spark/src/test/scala/org/apache/spark/sql/CometTestBase.scala
index 33c1d444b9..138b073b87 100644
--- a/spark/src/test/scala/org/apache/spark/sql/CometTestBase.scala
+++ b/spark/src/test/scala/org/apache/spark/sql/CometTestBase.scala
@@ -190,6 +190,17 @@ abstract class CometTestBase
     internalCheckSparkAnswer(df, assertCometNative = false, withTol = Some(absTol))
   }
 
+  /**
+   * Check that the query returns the correct results when Comet is enabled and that Comet
+   * replaced all possible operators. Use the provided `tol` when comparing floating-point
+   * results.
+   */
+  protected def checkSparkAnswerAndOperatorWithTolerance(
+      query: String,
+      absTol: Double = 1e-6): (SparkPlan, SparkPlan) = {
+    internalCheckSparkAnswer(sql(query), assertCometNative = true, withTol = Some(absTol))
+  }
+
   /**
    * Check that the query returns the correct results when Comet is enabled and that Comet
    * replaced all possible operators except for those specified in the excluded list.