diff --git a/velox/expression/CastExpr.cpp b/velox/expression/CastExpr.cpp
index c5c8ecb0bb79..1431a015e594 100644
--- a/velox/expression/CastExpr.cpp
+++ b/velox/expression/CastExpr.cpp
@@ -89,7 +89,10 @@ Status detail::parseDecimalComponents(
   // Optional exponent.
   if (s[pos] == 'e' || s[pos] == 'E') {
     ++pos;
-    bool withSign = pos < size && (s[pos] == '+' || s[pos] == '-');
+    if (pos == size) {
+      return Status::UserError("The exponent part is empty.");
+    }
+    bool withSign = s[pos] == '+' || s[pos] == '-';
     if (withSign && pos == size - 1) {
       return Status::UserError("The exponent part only contains sign.");
     }
@@ -98,17 +101,13 @@ Status detail::parseDecimalComponents(
     for (auto i = static_cast<size_t>(withSign); i < size - pos; ++i) {
       if (!std::isdigit(s[pos + i])) {
         return Status::UserError(
-            "Non-digit character '{}' is not allowed in the exponent part.",
-            s[pos + i]);
+            "Non-digit character is not allowed in the exponent part.");
       }
     }
     out.exponent = folly::to<int32_t>(folly::StringPiece(s + pos, size - pos));
     return Status::OK();
   }
-  return pos == size
-      ? Status::OK()
-      : Status::UserError(
-            "Chars '{}' are invalid.", std::string(s + pos, size - pos));
+  return pos == size ? Status::OK() : Status::UserError("Chars are invalid.");
 }
 
 Status detail::parseHugeInt(
diff --git a/velox/expression/fuzzer/SparkSpecialFormSignatureGenerator.cpp b/velox/expression/fuzzer/SparkSpecialFormSignatureGenerator.cpp
index 0c1cef30722a..36a801990c7c 100644
--- a/velox/expression/fuzzer/SparkSpecialFormSignatureGenerator.cpp
+++ b/velox/expression/fuzzer/SparkSpecialFormSignatureGenerator.cpp
@@ -27,8 +27,10 @@ SparkSpecialFormSignatureGenerator::getSignaturesForCast() const {
     signatures.push_back(makeCastSignature(fromType, "varbinary"));
   }
 
-  // Cast tinyint/smallint/integer/bigint as timestamp is supported in Spark.
-  for (auto fromType : {"tinyint", "smallint", "integer", "bigint"}) {
+  // Cast tinyint/smallint/integer/bigint/real/double as timestamp is supported
+  // in Spark.
+  for (auto fromType :
+       {"tinyint", "smallint", "integer", "bigint", "real", "double"}) {
     signatures.push_back(makeCastSignature(fromType, "timestamp"));
   }
   return signatures;
diff --git a/velox/expression/fuzzer/SpecialFormSignatureGenerator.cpp b/velox/expression/fuzzer/SpecialFormSignatureGenerator.cpp
index 0428e613422f..950dd98fc07f 100644
--- a/velox/expression/fuzzer/SpecialFormSignatureGenerator.cpp
+++ b/velox/expression/fuzzer/SpecialFormSignatureGenerator.cpp
@@ -51,6 +51,14 @@ void SpecialFormSignatureGenerator::addCastFromFloatingPointSignatures(
   }
 }
 
+void SpecialFormSignatureGenerator::addCastFromDecimalSignatures(
+    const std::string& toType,
+    std::vector<exec::FunctionSignaturePtr>& signatures) const {
+  for (const auto& fromType : kDecimalTypes_) {
+    signatures.push_back(makeCastSignature(fromType, toType));
+  }
+}
+
 void SpecialFormSignatureGenerator::addCastFromVarcharSignature(
     const std::string& toType,
     std::vector<exec::FunctionSignaturePtr>& signatures) const {
@@ -163,6 +171,7 @@ SpecialFormSignatureGenerator::getSignaturesForCast() const {
   for (const auto& toType : kIntegralTypes_) {
     addCastFromIntegralSignatures(toType, signatures);
     addCastFromFloatingPointSignatures(toType, signatures);
+    addCastFromDecimalSignatures(toType, signatures);
     addCastFromVarcharSignature(toType, signatures);
   }
 
@@ -170,12 +179,22 @@ SpecialFormSignatureGenerator::getSignaturesForCast() const {
   for (const auto& toType : kFloatingPointTypes_) {
     addCastFromIntegralSignatures(toType, signatures);
     addCastFromFloatingPointSignatures(toType, signatures);
+    addCastFromDecimalSignatures(toType, signatures);
+    addCastFromVarcharSignature(toType, signatures);
+  }
+
+  // To decimal type.
+  for (const auto& toType : kDecimalTypes_) {
+    addCastFromIntegralSignatures(toType, signatures);
+    addCastFromFloatingPointSignatures(toType, signatures);
+    addCastFromDecimalSignatures(toType, signatures);
     addCastFromVarcharSignature(toType, signatures);
   }
 
   // To varchar type.
   addCastFromIntegralSignatures("varchar", signatures);
   addCastFromFloatingPointSignatures("varchar", signatures);
+  addCastFromDecimalSignatures("varchar", signatures);
   addCastFromVarcharSignature("varchar", signatures);
   addCastFromDateSignature("varchar", signatures);
   addCastFromTimestampSignature("varchar", signatures);
@@ -195,6 +214,11 @@ SpecialFormSignatureGenerator::getSignaturesForCast() const {
     auto from = signatures[i]->argumentTypes()[0].baseName();
     auto to = signatures[i]->returnType().baseName();
 
+    // Signature parsing of nested decimal type is not supported.
+    if (from == "DECIMAL" || to == "DECIMAL") {
+      continue;
+    }
+
     signatures.push_back(makeCastSignature(
         fmt::format("array({})", from), fmt::format("array({})", to)));
 
diff --git a/velox/expression/fuzzer/SpecialFormSignatureGenerator.h b/velox/expression/fuzzer/SpecialFormSignatureGenerator.h
index 2b986872c77e..6882c4597f7d 100644
--- a/velox/expression/fuzzer/SpecialFormSignatureGenerator.h
+++ b/velox/expression/fuzzer/SpecialFormSignatureGenerator.h
@@ -45,8 +45,14 @@ class SpecialFormSignatureGenerator {
       const std::string& toType,
       std::vector<exec::FunctionSignaturePtr>& signatures) const;
 
-  /// Generates signatures for cast from varchar to the given type and adds them
-  /// to signatures.
+  /// Generates signatures for cast from decimal types to the given type
+  /// and adds them to signatures.
+  void addCastFromDecimalSignatures(
+      const std::string& toType,
+      std::vector<exec::FunctionSignaturePtr>& signatures) const;
+
+  /// Generates signatures for cast from varchar to the given type and adds
+  /// them to signatures.
   void addCastFromVarcharSignature(
       const std::string& toType,
       std::vector<exec::FunctionSignaturePtr>& signatures) const;
@@ -101,6 +107,12 @@ class SpecialFormSignatureGenerator {
       "boolean"};
 
   const std::vector<std::string> kFloatingPointTypes_{"real", "double"};
+
+  const std::vector<std::string> kDecimalTypes_{
+      "DECIMAL(6, 0)",
+      "DECIMAL(18, 6)",
+      "DECIMAL(38, 18)",
+      "DECIMAL(38, 38)"};
 };
 
 } // namespace facebook::velox::fuzzer
diff --git a/velox/expression/tests/CastExprTest.cpp b/velox/expression/tests/CastExprTest.cpp
index 198c8b34934d..89093b143770 100644
--- a/velox/expression/tests/CastExprTest.cpp
+++ b/velox/expression/tests/CastExprTest.cpp
@@ -2048,7 +2048,7 @@ TEST_F(CastExprTest, varcharToDecimal) {
       VARCHAR(),
       DECIMAL(38, 0),
       {"0.0444a"},
-      "Cannot cast VARCHAR '0.0444a' to DECIMAL(38, 0). Value is not a number. Chars 'a' are invalid.");
+      "Cannot cast VARCHAR '0.0444a' to DECIMAL(38, 0). Value is not a number.");
 
   testThrow<std::string>(
       VARCHAR(),
@@ -2081,29 +2081,29 @@ TEST_F(CastExprTest, varcharToDecimal) {
       VARCHAR(),
       DECIMAL(38, 0),
       {"23e-5d"},
-      "Cannot cast VARCHAR '23e-5d' to DECIMAL(38, 0). Value is not a number. Non-digit character 'd' is not allowed in the exponent part.");
+      "Cannot cast VARCHAR '23e-5d' to DECIMAL(38, 0). Value is not a number. Non-digit character is not allowed in the exponent part.");
 
   // Whitespaces.
   testThrow<std::string>(
       VARCHAR(),
       DECIMAL(38, 0),
       {"1. 23"},
-      "Cannot cast VARCHAR '1. 23' to DECIMAL(38, 0). Value is not a number. Chars ' 23' are invalid.");
+      "Cannot cast VARCHAR '1. 23' to DECIMAL(38, 0). Value is not a number.");
   testThrow<std::string>(
       VARCHAR(),
       DECIMAL(12, 2),
       {"-3E+ 2"},
-      "Cannot cast VARCHAR '-3E+ 2' to DECIMAL(12, 2). Value is not a number. Non-digit character ' ' is not allowed in the exponent part.");
+      "Cannot cast VARCHAR '-3E+ 2' to DECIMAL(12, 2). Value is not a number. Non-digit character is not allowed in the exponent part.");
   testThrow<std::string>(
       VARCHAR(),
       DECIMAL(38, 0),
       {"1.23 "},
-      "Cannot cast VARCHAR '1.23 ' to DECIMAL(38, 0). Value is not a number. Chars ' ' are invalid.");
+      "Cannot cast VARCHAR '1.23 ' to DECIMAL(38, 0). Value is not a number.");
   testThrow<std::string>(
       VARCHAR(),
       DECIMAL(12, 2),
       {"-3E+2 "},
-      "Cannot cast VARCHAR '-3E+2 ' to DECIMAL(12, 2). Value is not a number. Non-digit character ' ' is not allowed in the exponent part.");
+      "Cannot cast VARCHAR '-3E+2 ' to DECIMAL(12, 2). Value is not a number. Non-digit character is not allowed in the exponent part.");
   testThrow<std::string>(
       VARCHAR(),
       DECIMAL(38, 0),
@@ -2119,7 +2119,7 @@ TEST_F(CastExprTest, varcharToDecimal) {
       VARCHAR(),
       DECIMAL(12, 2),
       {"-3E+2.1"},
-      "Cannot cast VARCHAR '-3E+2.1' to DECIMAL(12, 2). Value is not a number. Non-digit character '.' is not allowed in the exponent part.");
+      "Cannot cast VARCHAR '-3E+2.1' to DECIMAL(12, 2). Value is not a number. Non-digit character is not allowed in the exponent part.");
 
   testThrow<std::string>(
       VARCHAR(),
@@ -2132,6 +2132,18 @@ TEST_F(CastExprTest, varcharToDecimal) {
       DECIMAL(12, 2),
       {"-3E-"},
       "Cannot cast VARCHAR '-3E-' to DECIMAL(12, 2). Value is not a number. The exponent part only contains sign.");
+
+  testThrow<std::string>(
+      VARCHAR(),
+      DECIMAL(12, 2),
+      {"9e"},
+      "Cannot cast VARCHAR '9e' to DECIMAL(12, 2). Value is not a number. The exponent part is empty.");
+
+  testThrow<std::string>(
+      VARCHAR(),
+      DECIMAL(12, 2),
+      {"09{xi+yD"},
+      "Cannot cast VARCHAR '09{xi+yD' to DECIMAL(12, 2). Value is not a number. Chars are invalid.");
 }
 
 TEST_F(CastExprTest, castInTry) {