diff --git a/MsgPack/Decoder.swift b/MsgPack/Decoder.swift
index f7ae951..48bb657 100644
--- a/MsgPack/Decoder.swift
+++ b/MsgPack/Decoder.swift
@@ -142,8 +142,8 @@ struct MsgPckSingleValueDecodingContainer: SingleValueDecodingContainer {
 		guard decoder.storage[base] == FormatID.float64.rawValue else {
 			throw Error.invalidFormat(decoder.storage[base])
 		}
-		let bitPattern: UInt64 = decoder.storage.read(at: base + 1)
-		return .init(bitPattern)
+		let bitPattern: UInt64 = decoder.storage.bigEndianInteger(at: base + 1)
+		return .init(bitPattern: bitPattern)
 	}
 	
 	func decode(_ type: String.Type) throws -> String {
diff --git a/Playground.playground/Contents.swift b/Playground.playground/Contents.swift
index 38e5849..b0cae1d 100644
--- a/Playground.playground/Contents.swift
+++ b/Playground.playground/Contents.swift
@@ -40,5 +40,5 @@ for byte in encodedGraph {
 
 let decoder = Decoder()
 
-let int8 = try encoder.encode(Int8(-57))
-try decoder.decode(Int8.self, from: int8)
+let int8 = try encoder.encode(Double(-10))
+try decoder.decode(Double.self, from: int8)