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 a184bc94ce..6aa161280a 100644
--- a/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala
+++ b/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala
@@ -630,7 +630,7 @@ object QueryPlanSerde extends Logging with CometExprShim {
       }
     }
 
-    expr match {
+    versionSpecificExprToProtoInternal(expr, inputs, binding).orElse(expr match {
       case a @ Alias(_, _) =>
         val r = exprToProtoInternal(a.child, inputs, binding)
         if (r.isEmpty) {
@@ -1284,25 +1284,6 @@ object QueryPlanSerde extends Logging with CometExprShim {
             optExprWithInfo(optExpr, expr, r.child)
         }
 
-      case s: StringDecode =>
-        // Right child is the encoding expression.
-        s.charset match {
-          case Literal(str, DataTypes.StringType)
-              if str.toString.toLowerCase(Locale.ROOT) == "utf-8" =>
-            // decode(col, 'utf-8') can be treated as a cast with "try" eval mode that puts nulls
-            // for invalid strings.
-            // Left child is the binary expression.
-            castToProto(
-              expr,
-              None,
-              DataTypes.StringType,
-              exprToProtoInternal(s.bin, inputs, binding).get,
-              CometEvalMode.TRY)
-          case _ =>
-            withInfo(expr, "Comet only supports decoding with 'utf-8'.")
-            None
-        }
-
       case RegExpReplace(subject, pattern, replacement, startPosition) =>
         if (!RegExp.isSupportedPattern(pattern.toString) &&
           !CometConf.COMET_REGEXP_ALLOW_INCOMPATIBLE.get()) {
@@ -1679,6 +1660,30 @@ object QueryPlanSerde extends Logging with CometExprShim {
             withInfo(expr, s"${expr.prettyName} is not supported", expr.children: _*)
             None
         }
+    })
+  }
+
+  def stringDecode(
+      expr: Expression,
+      charset: Expression,
+      bin: Expression,
+      inputs: Seq[Attribute],
+      binding: Boolean): Option[Expr] = {
+    charset match {
+      case Literal(str, DataTypes.StringType)
+          if str.toString.toLowerCase(Locale.ROOT) == "utf-8" =>
+        // decode(col, 'utf-8') can be treated as a cast with "try" eval mode that puts nulls
+        // for invalid strings.
+        // Left child is the binary expression.
+        castToProto(
+          expr,
+          None,
+          DataTypes.StringType,
+          exprToProtoInternal(bin, inputs, binding).get,
+          CometEvalMode.TRY)
+      case _ =>
+        withInfo(expr, "Comet only supports decoding with 'utf-8'.")
+        None
     }
   }
 
diff --git a/spark/src/main/spark-3.4/org/apache/comet/shims/CometExprShim.scala b/spark/src/main/spark-3.4/org/apache/comet/shims/CometExprShim.scala
index 5f4e3fba2b..2a302d8d41 100644
--- a/spark/src/main/spark-3.4/org/apache/comet/shims/CometExprShim.scala
+++ b/spark/src/main/spark-3.4/org/apache/comet/shims/CometExprShim.scala
@@ -19,6 +19,8 @@
 package org.apache.comet.shims
 
 import org.apache.comet.expressions.CometEvalMode
+import org.apache.comet.serde.ExprOuterClass.Expr
+import org.apache.comet.serde.QueryPlanSerde.stringDecode
 import org.apache.spark.sql.catalyst.expressions._
 
 /**
@@ -34,6 +36,19 @@ trait CometExprShim {
 
     protected def evalMode(c: Cast): CometEvalMode.Value =
         CometEvalModeUtil.fromSparkEvalMode(c.evalMode)
+
+    def versionSpecificExprToProtoInternal(
+        expr: Expression,
+        inputs: Seq[Attribute],
+        binding: Boolean): Option[Expr] = {
+      expr match {
+        case s: StringDecode =>
+          // Right child is the encoding expression.
+          stringDecode(expr, s.charset, s.bin, inputs, binding)
+
+        case _ => None
+      }
+    }
 }
 
 object CometEvalModeUtil {
diff --git a/spark/src/main/spark-3.5/org/apache/comet/shims/CometExprShim.scala b/spark/src/main/spark-3.5/org/apache/comet/shims/CometExprShim.scala
index 5f4e3fba2b..2a302d8d41 100644
--- a/spark/src/main/spark-3.5/org/apache/comet/shims/CometExprShim.scala
+++ b/spark/src/main/spark-3.5/org/apache/comet/shims/CometExprShim.scala
@@ -19,6 +19,8 @@
 package org.apache.comet.shims
 
 import org.apache.comet.expressions.CometEvalMode
+import org.apache.comet.serde.ExprOuterClass.Expr
+import org.apache.comet.serde.QueryPlanSerde.stringDecode
 import org.apache.spark.sql.catalyst.expressions._
 
 /**
@@ -34,6 +36,19 @@ trait CometExprShim {
 
     protected def evalMode(c: Cast): CometEvalMode.Value =
         CometEvalModeUtil.fromSparkEvalMode(c.evalMode)
+
+    def versionSpecificExprToProtoInternal(
+        expr: Expression,
+        inputs: Seq[Attribute],
+        binding: Boolean): Option[Expr] = {
+      expr match {
+        case s: StringDecode =>
+          // Right child is the encoding expression.
+          stringDecode(expr, s.charset, s.bin, inputs, binding)
+
+        case _ => None
+      }
+    }
 }
 
 object CometEvalModeUtil {
diff --git a/spark/src/main/spark-4.0/org/apache/comet/shims/CometExprShim.scala b/spark/src/main/spark-4.0/org/apache/comet/shims/CometExprShim.scala
index 5f4e3fba2b..1b8e5aaa04 100644
--- a/spark/src/main/spark-4.0/org/apache/comet/shims/CometExprShim.scala
+++ b/spark/src/main/spark-4.0/org/apache/comet/shims/CometExprShim.scala
@@ -19,7 +19,12 @@
 package org.apache.comet.shims
 
 import org.apache.comet.expressions.CometEvalMode
+import org.apache.comet.serde.ExprOuterClass.Expr
+import org.apache.comet.serde.QueryPlanSerde.stringDecode
 import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.catalyst.expressions.objects.StaticInvoke
+import org.apache.spark.sql.internal.types.StringTypeWithCollation
+import org.apache.spark.sql.types.{BinaryType, BooleanType, StringType}
 
 /**
  * `CometExprShim` acts as a shim for for parsing expressions from different Spark versions.
@@ -34,6 +39,28 @@ trait CometExprShim {
 
     protected def evalMode(c: Cast): CometEvalMode.Value =
         CometEvalModeUtil.fromSparkEvalMode(c.evalMode)
+
+    def versionSpecificExprToProtoInternal(
+        expr: Expression,
+        inputs: Seq[Attribute],
+        binding: Boolean): Option[Expr] = {
+      expr match {
+        case s: StaticInvoke
+            if s.staticObject == classOf[StringDecode] &&
+              s.dataType.isInstanceOf[StringType] &&
+              s.functionName == "decode" &&
+              s.arguments.size == 4 &&
+              s.inputTypes == Seq(
+                  BinaryType,
+                  StringTypeWithCollation(supportsTrimCollation = true),
+                  BooleanType,
+                  BooleanType) =>
+          val Seq(bin, charset, _, _) = s.arguments
+          stringDecode(expr, charset, bin, inputs, binding)
+
+        case _ => None
+      }
+    }
 }
 
 object CometEvalModeUtil {
diff --git a/spark/src/test/scala/org/apache/comet/CometFuzzTestSuite.scala b/spark/src/test/scala/org/apache/comet/CometFuzzTestSuite.scala
index d1f55cbe1e..a1b1812b31 100644
--- a/spark/src/test/scala/org/apache/comet/CometFuzzTestSuite.scala
+++ b/spark/src/test/scala/org/apache/comet/CometFuzzTestSuite.scala
@@ -38,7 +38,6 @@ import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.internal.SQLConf.ParquetOutputTimestampType
 import org.apache.spark.sql.types._
 
-import org.apache.comet.CometSparkSessionExtensions.isSpark40Plus
 import org.apache.comet.testing.{DataGenOptions, ParquetGenerator}
 
 class CometFuzzTestSuite extends CometTestBase with AdaptiveSparkPlanHelper {
@@ -272,8 +271,6 @@ class CometFuzzTestSuite extends CometTestBase with AdaptiveSparkPlanHelper {
   }
 
   test("decode") {
-    // https://github.com/apache/datafusion-comet/issues/1942
-    assume(!isSpark40Plus)
     val df = spark.read.parquet(filename)
     df.createOrReplaceTempView("t1")
     // We want to make sure that the schema generator wasn't modified to accidentally omit