diff --git a/EosioSwift/Extensions/DataExtensions.swift b/EosioSwift/Extensions/DataExtensions.swift
index 5569a319..d77d1709 100644
--- a/EosioSwift/Extensions/DataExtensions.swift
+++ b/EosioSwift/Extensions/DataExtensions.swift
@@ -57,19 +57,38 @@ public extension Data {
     ///
     /// - Parameter hexString: A Base16 encoded string.
     init?(hexString: String) {
+        guard let hexData = hexString.data(using: .ascii) else { return nil }
+
         let len = hexString.count / 2
-        var data = Data(capacity: len)
-        for i in 0..<len {
-            let j = hexString.index(hexString.startIndex, offsetBy: i*2) // swiftlint:disable:this identifier_name
-            let k = hexString.index(j, offsetBy: 2) // swiftlint:disable:this identifier_name
-            let bytes = hexString[j..<k]
-            if var num = UInt8(bytes, radix: 16) {
-                data.append(&num, count: 1)
-            } else {
-                return nil
+        var data: Data?
+
+        hexData.withUnsafeBytes { ptr in
+            var dataPtrOffset = 0
+
+            guard let baseAddress = ptr.baseAddress else { return }
+            let dataPtr = UnsafeMutablePointer<UInt8>.allocate(capacity: len)
+
+            for offset in stride(from: 0, to: hexString.count, by: 2) {
+                let bytes = Data(bytes: baseAddress+offset, count: 2)
+
+                guard let string = String(data: bytes, encoding: .ascii) else {
+                    dataPtr.deallocate()
+                    return
+                }
+
+                guard let num = UInt8(string, radix: 16) else {
+                    dataPtr.deallocate()
+                    return
+                }
+                dataPtr[dataPtrOffset] = num
+                dataPtrOffset += 1
             }
+
+            data = Data(bytesNoCopy: dataPtr, count: len, deallocator: .free)
         }
-        self = data
+
+        guard let validData = data else { return nil }
+        self = validData
     }
 
     /// Returns the SHA256 hash of the data.
diff --git a/EosioSwiftTests/DataExtensionsTests.swift b/EosioSwiftTests/DataExtensionsTests.swift
index f8d4c577..28773063 100644
--- a/EosioSwiftTests/DataExtensionsTests.swift
+++ b/EosioSwiftTests/DataExtensionsTests.swift
@@ -37,6 +37,12 @@ class DataExtensionsTests: XCTestCase {
         XCTAssertNotNil(data)
     }
 
+    func test_initWithHexString_withLargeValidHexString_shouldSucceed() {
+        // swiftlint:disable:next line_length
+        let data = Data(hexString: "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+        XCTAssertNotNil(data)
+    }
+
     func test_initWithHexString_withInvalidStringArgument_shouldReturnNil() {
         let data = Data(hexString: "Some invalid string")
         XCTAssertNil(data)