diff --git a/calnex/firmware/firmware.go b/calnex/firmware/firmware.go
index 0a4d9349..ebe44ed6 100644
--- a/calnex/firmware/firmware.go
+++ b/calnex/firmware/firmware.go
@@ -51,7 +51,9 @@ func (up CalnexUpgrader) ShouldUpgrade(target string, api *calnexAPI.API, fw FW,
 	if err != nil {
 		return false, err
 	}
-	calnexVersion, err := version.NewVersion(strings.ToLower(cv.Firmware))
+	//remove major version 2.17.0 -> 17.0 as this is hadware revision related
+	//calnexVersion, err := version.NewVersion(strings.ToLower(cv.Firmware))
+	calnexVersion, err := version.NewVersion(strings.ToLower(strings.SplitN(cv.Firmware, ".", 2)[1]))
 	if err != nil {
 		return false, err
 	}
diff --git a/calnex/firmware/ossfirmware.go b/calnex/firmware/ossfirmware.go
index 803d46ab..b8c611ff 100644
--- a/calnex/firmware/ossfirmware.go
+++ b/calnex/firmware/ossfirmware.go
@@ -17,7 +17,9 @@ limitations under the License.
 package firmware
 
 import (
+	"fmt"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	version "github.com/hashicorp/go-version"
@@ -31,12 +33,34 @@ type OSSFW struct {
 
 // NewOSSFW returns initialized version of OSSFW
 func NewOSSFW(source string) (*OSSFW, error) {
+	var vs string
+
 	fw := &OSSFW{
 		filepath: source,
 	}
+
 	basename := filepath.Base(fw.filepath)
-	vs := strings.ReplaceAll(strings.TrimSuffix(basename, filepath.Ext(basename)), "sentinel_fw_v", "")
+	// Extract version from filename
+	// sentinel_fw_v2.13.1.0.5583D-20210924.tar -> 13.1.0.5583
+	// calnex_combined_fw_R21.0.0.9705-20241111.tar -> 21.0.0.9705
+
+	re := regexp.MustCompile(`(sentry_fw_|sentinel_fw_|calnex_combined_fw_)(v[0-9]\.|R)(.*)\.tar`)
+
+	matches := re.FindStringSubmatch(basename)
+
+	if len(matches) == 4 {
+		vs = matches[3]
+	} else {
+		return nil, fmt.Errorf("invalid filename, expected prefix sentinel_fw_, sentry_fw_, or calnex_combined_fw_ followed by 'v2.' or 'R': %s", basename)
+	}
 	v, err := version.NewVersion(strings.ToLower(vs))
+	if err != nil {
+		return nil, err
+	}
+	//expect major, minor, patch, build
+	if len(v.Segments()) != 4 {
+		return nil, fmt.Errorf("invalid version format, expected 4 segments: %v", v.Segments())
+	}
 	fw.version = v
 	return fw, err
 }
diff --git a/calnex/firmware/ossfirmware_test.go b/calnex/firmware/ossfirmware_test.go
index f03c6668..66bac20b 100644
--- a/calnex/firmware/ossfirmware_test.go
+++ b/calnex/firmware/ossfirmware_test.go
@@ -23,9 +23,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestOSSFW(t *testing.T) {
-	expectedFilePath := "/tmp/sentinel_fw_v2.13.1.0.5583D-20210924.tar"
-	expectedVersion, _ := version.NewVersion("2.13.1.0.5583d-20210924")
+func checkOSSFW(t *testing.T, expectedFilePath string, expectedVersion *version.Version) {
 	fw, err := NewOSSFW(expectedFilePath)
 	require.NoError(t, err)
 
@@ -37,3 +35,82 @@ func TestOSSFW(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, expectedVersion, v)
 }
+
+func checkErrorOSSFW(t *testing.T, expectedFilePath string) {
+	fw, err := NewOSSFW(expectedFilePath)
+	require.Nil(t, fw)
+	require.Error(t, err)
+}
+
+func TestOSSFW(t *testing.T) {
+	//all files are expected to produce the same version output
+	//development/beta build versions (D after build number)
+	expectedVersiondev, _ := version.NewVersion("13.1.0.5583d-20210924")
+
+	// Test case for sentinel_fw
+	expectedFilePathSentineldev := "/tmp/sentinel_fw_v2.13.1.0.5583D-20210924.tar"
+	checkOSSFW(t, expectedFilePathSentineldev, expectedVersiondev)
+
+	// Test case for sentry
+	expectedFilePathSentrydev := "/tmp/sentry_fw_v2.13.1.0.5583D-20210924.tar"
+	checkOSSFW(t, expectedFilePathSentrydev, expectedVersiondev)
+
+	// Test case for calnex_combined
+	expectedFilePathCalnexdev := "/tmp/calnex_combined_fw_R13.1.0.5583D-20210924.tar"
+	checkOSSFW(t, expectedFilePathCalnexdev, expectedVersiondev)
+
+	//full release versions (no D)
+	expectedVersion, _ := version.NewVersion("13.1.0.5583-20210924")
+
+	// Test case for sentinel_fw
+	expectedFilePathSentinel := "/tmp/sentinel_fw_v2.13.1.0.5583-20210924.tar"
+	checkOSSFW(t, expectedFilePathSentinel, expectedVersion)
+
+	// Test case for sentry
+	expectedFilePathSentry := "/tmp/sentry_fw_v2.13.1.0.5583-20210924.tar"
+	checkOSSFW(t, expectedFilePathSentry, expectedVersion)
+
+	// Test case for calnex_combined
+	expectedFilePathCalnex := "/tmp/calnex_combined_fw_R13.1.0.5583-20210924.tar"
+	checkOSSFW(t, expectedFilePathCalnex, expectedVersion)
+
+	// Check errors
+	expectedFilePathMissingStart := "/tmp/R13.1.0.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathMissingStart)
+
+	//missing v2./R
+	expectedFilePathMissingSecond := "/tmp/sentinel_fw_13.1.0.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathMissingSecond)
+
+	//misspelt sintinel
+	expectedFilePathBadStart := "/tmp/sentrinel_fw_R13.1.0.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathBadStart)
+
+	//both v2. and R
+	expectedFilePathBadSecond := "/tmp/sentinel_fw_Rv2.13.1.0.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathBadSecond)
+
+	//.zip not .tar
+	expectedFilePathBadExtension := "/tmp/sentinel_fw_R13.1.0.5583-20210924.zip"
+	checkErrorOSSFW(t, expectedFilePathBadExtension)
+
+	//HW version not 0-9
+	expectedFilePathBadHWVersion := "/tmp/sentinel_fw_v10.13.1.0.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathBadHWVersion)
+
+	//malformed versions
+	expectedFilePathBadBuild1 := "/tmp/sentinel_fw_v2.13.1.0.D5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathBadBuild1)
+
+	expectedFilePathBadBuild2 := "/tmp/sentinel_fw_v2.13.1D.0.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathBadBuild2)
+
+	expectedFilePathBadBuild3 := "/tmp/sentinel_fw_v2.13D.1.0.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathBadBuild3)
+
+	expectedFilePathBadBuild4 := "/tmp/sentinel_fw_v2.13.1..10.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathBadBuild4)
+
+	expectedFilePathBadBuild5 := "/tmp/sentinel_fw_v2.13.1.1.10.5583-20210924.tar"
+	checkErrorOSSFW(t, expectedFilePathBadBuild5)
+}