diff --git a/src/providers/completion-item/version.ts b/src/providers/completion-item/version.ts
index 19cff1f..06e415a 100644
--- a/src/providers/completion-item/version.ts
+++ b/src/providers/completion-item/version.ts
@@ -2,7 +2,7 @@ import type { Extractor } from '#types/extractor'
 import type { CompletionItemProvider, Position, TextDocument } from 'vscode'
 import { config } from '#state'
 import { getPackageInfo } from '#utils/api/package'
-import { formatVersion, parseVersion } from '#utils/package'
+import { formatVersion, isSupportedProtocol, parseVersion } from '#utils/package'
 import { CompletionItem, CompletionItemKind } from 'vscode'
 
 export class VersionCompletionItemProvider<T extends Extractor> implements CompletionItemProvider {
@@ -29,7 +29,7 @@ export class VersionCompletionItemProvider<T extends Extractor> implements Compl
     } = info
 
     const parsed = parseVersion(version)
-    if (!parsed)
+    if (!parsed || !isSupportedProtocol(parsed.protocol))
       return
 
     const pkg = await getPackageInfo(name)
diff --git a/src/providers/diagnostics/rules/deprecation.ts b/src/providers/diagnostics/rules/deprecation.ts
index 70bfe90..a0b6a6a 100644
--- a/src/providers/diagnostics/rules/deprecation.ts
+++ b/src/providers/diagnostics/rules/deprecation.ts
@@ -1,11 +1,11 @@
 import type { DiagnosticRule } from '..'
 import { npmxPackageUrl } from '#utils/links'
-import { parseVersion } from '#utils/package'
+import { isSupportedProtocol, parseVersion } from '#utils/package'
 import { DiagnosticSeverity, DiagnosticTag, Uri } from 'vscode'
 
 export const checkDeprecation: DiagnosticRule = (dep, pkg) => {
   const parsed = parseVersion(dep.version)
-  if (!parsed)
+  if (!parsed || !isSupportedProtocol(parsed.protocol))
     return
 
   const { semver } = parsed
diff --git a/src/providers/diagnostics/rules/vulnerability.ts b/src/providers/diagnostics/rules/vulnerability.ts
index e89f67c..01cbc08 100644
--- a/src/providers/diagnostics/rules/vulnerability.ts
+++ b/src/providers/diagnostics/rules/vulnerability.ts
@@ -2,7 +2,7 @@ import type { OsvSeverityLevel } from '#utils/api/vulnerability'
 import type { DiagnosticRule } from '..'
 import { getVulnerability, SEVERITY_LEVELS } from '#utils/api/vulnerability'
 import { npmxPackageUrl } from '#utils/links'
-import { parseVersion } from '#utils/package'
+import { isSupportedProtocol, parseVersion } from '#utils/package'
 import { DiagnosticSeverity, Uri } from 'vscode'
 
 const DIAGNOSTIC_MAPPING: Record<Exclude<OsvSeverityLevel, 'unknown'>, DiagnosticSeverity> = {
@@ -14,7 +14,7 @@ const DIAGNOSTIC_MAPPING: Record<Exclude<OsvSeverityLevel, 'unknown'>, Diagnosti
 
 export const checkVulnerability: DiagnosticRule = async (dep, pkg) => {
   const parsed = parseVersion(dep.version)
-  if (!parsed)
+  if (!parsed || !isSupportedProtocol(parsed.protocol))
     return
 
   const { semver } = parsed
diff --git a/src/providers/hover/npmx.ts b/src/providers/hover/npmx.ts
index ab18522..afd32d2 100644
--- a/src/providers/hover/npmx.ts
+++ b/src/providers/hover/npmx.ts
@@ -3,7 +3,7 @@ import type { HoverProvider, Position, TextDocument } from 'vscode'
 import { SPACER } from '#constants'
 import { getPackageInfo } from '#utils/api/package'
 import { npmPacakgeUrl, npmxDocsUrl, npmxPackageUrl } from '#utils/links'
-import { parseVersion } from '#utils/package'
+import { isSupportedProtocol, parseVersion } from '#utils/package'
 import { Hover, MarkdownString } from 'vscode'
 
 export class NpmxHoverProvider<T extends Extractor> implements HoverProvider {
@@ -24,7 +24,7 @@ export class NpmxHoverProvider<T extends Extractor> implements HoverProvider {
       return
 
     const parsed = parseVersion(dep.version)
-    if (!parsed)
+    if (!parsed || !isSupportedProtocol(parsed.protocol))
       return
 
     const { name } = dep
diff --git a/src/utils/package.ts b/src/utils/package.ts
index 8043e05..487798e 100644
--- a/src/utils/package.ts
+++ b/src/utils/package.ts
@@ -9,13 +9,11 @@ export function encodePackageName(name: string): string {
   return encodeURIComponent(name)
 }
 
-const WORKSPACE_PREFIX = 'workspace:'
-const CATALOG_PREFIX = 'catalog:'
-const NPM_PREFIX = 'npm:'
-const JSR_PREFIX = 'jsr:'
-const URL_PREFIXES = ['http://', 'https://', 'git://', 'git+']
+export type VersionProtocol = 'workspace' | 'catalog' | 'npm' | 'jsr' | null
 
-export type VersionProtocol = 'npm' | null
+const KNOWN_PROTOCOLS = new Set<VersionProtocol>(['workspace', 'catalog', 'npm', 'jsr'])
+const URL_PREFIXES = ['http://', 'https://', 'git://', 'git+']
+const UNSUPPORTED_PROTOCOLS = new Set<VersionProtocol>(['workspace', 'catalog', 'jsr'])
 
 export interface ParsedVersion {
   protocol: VersionProtocol
@@ -23,31 +21,33 @@ export interface ParsedVersion {
   semver: string
 }
 
+export function isSupportedProtocol(protocol: VersionProtocol): boolean {
+  return !UNSUPPORTED_PROTOCOLS.has(protocol)
+}
+
 export function formatVersion(parsed: ParsedVersion): string {
   const protocol = parsed.protocol ? `${parsed.protocol}:` : ''
   return `${protocol}${parsed.prefix}${parsed.semver}`
 }
 
 export function parseVersion(rawVersion: string): ParsedVersion | null {
-  // Skip special protocols that aren't standard npm versions
-  if (
-    [
-      WORKSPACE_PREFIX,
-      CATALOG_PREFIX,
-      JSR_PREFIX,
-      ...URL_PREFIXES,
-    ].some((p) => rawVersion.startsWith(p))
-  ) {
+  rawVersion = rawVersion.trim()
+  // Skip URL-based versions
+  if (URL_PREFIXES.some((p) => rawVersion.startsWith(p)))
     return null
-  }
 
   let protocol: VersionProtocol = null
   let versionStr = rawVersion
 
-  // Handle npm: protocol (e.g., npm:^1.0.0)
-  if (rawVersion.startsWith(NPM_PREFIX)) {
-    protocol = 'npm'
-    versionStr = rawVersion.slice(4 /* NPM_PREFIX.length */)
+  // Parse protocol if present (e.g., npm:^1.0.0 -> protocol: 'npm')
+  const colonIndex = rawVersion.indexOf(':')
+  if (colonIndex !== -1) {
+    protocol = rawVersion.slice(0, colonIndex) as VersionProtocol
+
+    if (!KNOWN_PROTOCOLS.has(protocol))
+      return null
+
+    versionStr = rawVersion.slice(colonIndex + 1)
   }
 
   const firstChar = versionStr[0]
diff --git a/tests/package.test.ts b/tests/package.test.ts
index 3f3895e..7eb5ecd 100644
--- a/tests/package.test.ts
+++ b/tests/package.test.ts
@@ -52,15 +52,33 @@ describe('parseVersion', () => {
     })
   })
 
-  it('should return null for workspace:', () => {
-    expect(parseVersion('workspace:*')).toBeNull()
+  it('should parse workspace: protocol', () => {
+    expect(parseVersion('workspace:*')).toEqual({
+      protocol: 'workspace',
+      prefix: '',
+      semver: '*',
+    })
+  })
+
+  it('should parse catalog: protocol', () => {
+    expect(parseVersion('catalog:default')).toEqual({
+      protocol: 'catalog',
+      prefix: '',
+      semver: 'default',
+    })
   })
 
-  it('should return null for catalog:', () => {
-    expect(parseVersion('catalog:default')).toBeNull()
+  it('should parse jsr: protocol', () => {
+    expect(parseVersion('jsr:^1.1.4')).toEqual({
+      protocol: 'jsr',
+      prefix: '^',
+      semver: '1.1.4',
+    })
   })
 
-  it('should return null for jsr:', () => {
-    expect(parseVersion('jsr:@std/fs')).toBeNull()
+  it('should return null for URL-based versions', () => {
+    expect(parseVersion('https://github.com/user/repo')).toBeNull()
+    expect(parseVersion('git://github.com/user/repo')).toBeNull()
+    expect(parseVersion('git+https://github.com/user/repo')).toBeNull()
   })
 })