diff --git a/cmd/fs-v1-multipart.go b/cmd/fs-v1-multipart.go
index 427f12ef6..f3476ccda 100644
--- a/cmd/fs-v1-multipart.go
+++ b/cmd/fs-v1-multipart.go
@@ -482,6 +482,11 @@ func (fs fsObjects) PutObjectPart(bucket, object, uploadID string, partID int, d
 		return pi, toObjectErr(err, bucket)
 	}
 
+	// Validate input data size and it can never be less than zero.
+	if data.Size() < 0 {
+		return pi, toObjectErr(traceError(errInvalidArgument))
+	}
+
 	// Hold the lock so that two parallel complete-multipart-uploads
 	// do not leave a stale uploads.json behind.
 	objectMPartPathLock := globalNSMutex.NewNSLock(minioMetaMultipartBucket, pathJoin(bucket, object))
diff --git a/cmd/fs-v1.go b/cmd/fs-v1.go
index a672791c1..11e4d8775 100644
--- a/cmd/fs-v1.go
+++ b/cmd/fs-v1.go
@@ -537,6 +537,11 @@ func (fs fsObjects) PutObject(bucket string, object string, data *HashReader, me
 		return ObjectInfo{}, toObjectErr(traceError(errFileAccessDenied), bucket, object)
 	}
 
+	// Validate input data size and it can never be less than zero.
+	if data.Size() < 0 {
+		return ObjectInfo{}, traceError(errInvalidArgument)
+	}
+
 	// No metadata is set, allocate a new one.
 	if metadata == nil {
 		metadata = make(map[string]string)
diff --git a/cmd/xl-v1-multipart.go b/cmd/xl-v1-multipart.go
index 4163096af..f392b177e 100644
--- a/cmd/xl-v1-multipart.go
+++ b/cmd/xl-v1-multipart.go
@@ -577,6 +577,11 @@ func (xl xlObjects) PutObjectPart(bucket, object, uploadID string, partID int, d
 		return pi, err
 	}
 
+	// Validate input data size and it can never be less than zero.
+	if data.Size() < 0 {
+		return pi, toObjectErr(traceError(errInvalidArgument))
+	}
+
 	var partsMetadata []xlMetaV1
 	var errs []error
 	uploadIDPath := pathJoin(bucket, object, uploadID)
@@ -586,6 +591,7 @@ func (xl xlObjects) PutObjectPart(bucket, object, uploadID string, partID int, d
 	if err := preUploadIDLock.GetRLock(globalOperationTimeout); err != nil {
 		return pi, err
 	}
+
 	// Validates if upload ID exists.
 	if !xl.isUploadIDExists(bucket, object, uploadID) {
 		preUploadIDLock.RUnlock()
diff --git a/cmd/xl-v1-object.go b/cmd/xl-v1-object.go
index 1dd954671..1408a4fa1 100644
--- a/cmd/xl-v1-object.go
+++ b/cmd/xl-v1-object.go
@@ -443,6 +443,11 @@ func (xl xlObjects) PutObject(bucket string, object string, data *HashReader, me
 		return ObjectInfo{}, err
 	}
 
+	// Validate input data size and it can never be less than zero.
+	if data.Size() < 0 {
+		return ObjectInfo{}, toObjectErr(traceError(errInvalidArgument))
+	}
+
 	// Check if an object is present as one of the parent dir.
 	// -- FIXME. (needs a new kind of lock).
 	// -- FIXME (this also causes performance issue when disks are down).
@@ -504,7 +509,10 @@ func (xl xlObjects) PutObject(bucket string, object string, data *HashReader, me
 	if err != nil {
 		return ObjectInfo{}, toObjectErr(err, bucket, object)
 	}
-	buffer := make([]byte, partsMetadata[0].Erasure.BlockSize, 2*partsMetadata[0].Erasure.BlockSize) // alloc additional space for parity blocks created while erasure coding
+
+	// Alloc additional space for parity blocks created while erasure codinga
+	buffer := make([]byte, partsMetadata[0].Erasure.BlockSize, 2*partsMetadata[0].Erasure.BlockSize)
+
 	// Read data and split into parts - similar to multipart mechanism
 	for partIdx := 1; ; partIdx++ {
 		// Compute part name
@@ -512,10 +520,10 @@ func (xl xlObjects) PutObject(bucket string, object string, data *HashReader, me
 		// Compute the path of current part
 		tempErasureObj := pathJoin(uniqueID, partName)
 
-		// Calculate the size of the current part, if size is unknown, curPartSize wil be unknown too.
-		// allowEmptyPart will always be true if this is the first part and false otherwise.
+		// Calculate the size of the current part. AllowEmptyPart will always be true
+		// if this is the first part and false otherwise.
 		var curPartSize int64
-		curPartSize, err = getPartSizeFromIdx(data.Size(), globalPutPartSize, partIdx)
+		curPartSize, err = calculatePartSizeFromIdx(data.Size(), globalPutPartSize, partIdx)
 		if err != nil {
 			return ObjectInfo{}, toObjectErr(err, bucket, object)
 		}
@@ -529,7 +537,8 @@ func (xl xlObjects) PutObject(bucket string, object string, data *HashReader, me
 			}
 		}
 
-		file, erasureErr := storage.CreateFile(io.LimitReader(reader, globalPutPartSize), minioMetaTmpBucket, tempErasureObj, buffer, DefaultBitrotAlgorithm, xl.writeQuorum)
+		file, erasureErr := storage.CreateFile(io.LimitReader(reader, curPartSize), minioMetaTmpBucket,
+			tempErasureObj, buffer, DefaultBitrotAlgorithm, xl.writeQuorum)
 		if erasureErr != nil {
 			return ObjectInfo{}, toObjectErr(erasureErr, minioMetaTmpBucket, tempErasureObj)
 		}
@@ -561,7 +570,7 @@ func (xl xlObjects) PutObject(bucket string, object string, data *HashReader, me
 
 		// Check part size for the next index.
 		var partSize int64
-		partSize, err = getPartSizeFromIdx(data.Size(), globalPutPartSize, partIdx+1)
+		partSize, err = calculatePartSizeFromIdx(data.Size(), globalPutPartSize, partIdx+1)
 		if err != nil {
 			return ObjectInfo{}, toObjectErr(err, bucket, object)
 		}
@@ -570,7 +579,7 @@ func (xl xlObjects) PutObject(bucket string, object string, data *HashReader, me
 		}
 	}
 
-	if size := data.Size(); size > 0 && sizeWritten < data.Size() {
+	if sizeWritten < data.Size() {
 		return ObjectInfo{}, traceError(IncompleteBody{})
 	}
 
diff --git a/cmd/xl-v1-utils.go b/cmd/xl-v1-utils.go
index 087574c9a..b1f6dd674 100644
--- a/cmd/xl-v1-utils.go
+++ b/cmd/xl-v1-utils.go
@@ -382,35 +382,37 @@ func evalDisks(disks []StorageAPI, errs []error) []StorageAPI {
 	return newDisks
 }
 
-// Errors specifically generated by getPartSizeFromIdx function.
+// Errors specifically generated by calculatePartSizeFromIdx function.
 var (
 	errPartSizeZero  = errors.New("Part size cannot be zero")
 	errPartSizeIndex = errors.New("Part index cannot be smaller than 1")
 )
 
-// getPartSizeFromIdx predicts the part size according to its index. It also
-// returns -1 when totalSize is -1.
-func getPartSizeFromIdx(totalSize int64, partSize int64, partIndex int) (int64, error) {
+// calculatePartSizeFromIdx calculates the part size according to input index.
+// returns error if totalSize is -1, partSize is 0, partIndex is 0.
+func calculatePartSizeFromIdx(totalSize int64, partSize int64, partIndex int) (currPartSize int64, err error) {
+	if totalSize < 0 {
+		return 0, traceError(errInvalidArgument)
+	}
 	if partSize == 0 {
 		return 0, traceError(errPartSizeZero)
 	}
 	if partIndex < 1 {
 		return 0, traceError(errPartSizeIndex)
 	}
-	switch totalSize {
-	case -1, 0:
-		return totalSize, nil
-	}
-	// Compute the total count of parts
-	partsCount := totalSize/partSize + 1
-	// Return the part's size
-	switch {
-	case int64(partIndex) < partsCount:
-		return partSize, nil
-	case int64(partIndex) == partsCount:
-		// Size of last part
-		return totalSize % partSize, nil
-	default:
-		return 0, nil
+	if totalSize > 0 {
+		// Compute the total count of parts
+		partsCount := totalSize/partSize + 1
+		// Return the part's size
+		switch {
+		case int64(partIndex) < partsCount:
+			currPartSize = partSize
+		case int64(partIndex) == partsCount:
+			// Size of last part
+			currPartSize = totalSize % partSize
+		default:
+			currPartSize = 0
+		}
 	}
+	return currPartSize, nil
 }
diff --git a/cmd/xl-v1-utils_test.go b/cmd/xl-v1-utils_test.go
index de6bdb947..bc160eea1 100644
--- a/cmd/xl-v1-utils_test.go
+++ b/cmd/xl-v1-utils_test.go
@@ -340,8 +340,6 @@ func TestGetPartSizeFromIdx(t *testing.T) {
 		partIndex    int
 		expectedSize int64
 	}{
-		// Total size is - 1
-		{-1, 10, 1, -1},
 		// Total size is zero
 		{0, 10, 1, 0},
 		// part size 2MiB, total size 4MiB
@@ -356,7 +354,7 @@ func TestGetPartSizeFromIdx(t *testing.T) {
 	}
 
 	for i, testCase := range testCases {
-		s, err := getPartSizeFromIdx(testCase.totalSize, testCase.partSize, testCase.partIndex)
+		s, err := calculatePartSizeFromIdx(testCase.totalSize, testCase.partSize, testCase.partIndex)
 		if err != nil {
 			t.Errorf("Test %d: Expected to pass but failed. %s", i+1, err)
 		}
@@ -371,13 +369,16 @@ func TestGetPartSizeFromIdx(t *testing.T) {
 		partIndex int
 		err       error
 	}{
-		// partSize is 0, error.
+		// partSize is 0, returns error.
 		{10, 0, 1, errPartSizeZero},
+		// partIndex is 0, returns error.
 		{10, 1, 0, errPartSizeIndex},
+		// Total size is -1, returns error.
+		{-1, 10, 1, errInvalidArgument},
 	}
 
 	for i, testCaseFailure := range testCasesFailure {
-		_, err := getPartSizeFromIdx(testCaseFailure.totalSize, testCaseFailure.partSize, testCaseFailure.partIndex)
+		_, err := calculatePartSizeFromIdx(testCaseFailure.totalSize, testCaseFailure.partSize, testCaseFailure.partIndex)
 		if err == nil {
 			t.Errorf("Test %d: Expected to failed but passed. %s", i+1, err)
 		}