diff --git a/go.mod b/go.mod
index b5341fa..d2e7208 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,6 @@ module github.com/git-pkgs/purl
 go 1.25.6
 
 require (
-	github.com/git-pkgs/vers v0.3.1
+	github.com/git-pkgs/vers v0.6.0
 	github.com/package-url/packageurl-go v0.1.7
 )
diff --git a/go.sum b/go.sum
index beb0db0..8e48ab8 100644
--- a/go.sum
+++ b/go.sum
@@ -1,4 +1,4 @@
-github.com/git-pkgs/vers v0.3.1 h1:jy/ht2wIRJI5zQrccm6GTeYr+hGFwe2z8LV1HOr4Wco=
-github.com/git-pkgs/vers v0.3.1/go.mod h1:biTbSQK1qdbrsxDEKnqe3Jzclxz8vW6uDcwKjfUGcOo=
+github.com/git-pkgs/vers v0.6.0 h1:droJw8+oSyl8/UoDj/96B9ZPggmxJDTl/JeixzfKzSc=
+github.com/git-pkgs/vers v0.6.0/go.mod h1:biTbSQK1qdbrsxDEKnqe3Jzclxz8vW6uDcwKjfUGcOo=
 github.com/package-url/packageurl-go v0.1.7 h1:iFWg6tzAjLA6F/qX3M5nZaiMHJgc+p2zxVyr/fY+sZY=
 github.com/package-url/packageurl-go v0.1.7/go.mod h1:nKAWB8E6uk1MHqiS/lQb9pYBGH2+mdJ2PJc2s50dQY0=
diff --git a/makepurl.go b/makepurl.go
index 37255f2..ac3cb8f 100644
--- a/makepurl.go
+++ b/makepurl.go
@@ -7,13 +7,16 @@ import (
 	packageurl "github.com/package-url/packageurl-go"
 )
 
-// CleanVersion extracts a version from a version constraint string.
-// Uses the vers library to parse the constraint and extract the minimum bound.
-// If parsing fails, returns the original string.
+// CleanVersion returns plain versions unchanged. For version constraints, it
+// uses the vers library to extract the minimum bound. If parsing fails, it
+// returns the original string.
 func CleanVersion(version, scheme string) string {
 	if version == "" {
 		return ""
 	}
+	if !hasConstraintSyntax(version, scheme) && vers.ValidWithScheme(version, scheme) {
+		return version
+	}
 
 	r, err := vers.ParseNative(version, scheme)
 	if err != nil || len(r.Intervals) == 0 {
@@ -28,6 +31,29 @@ func CleanVersion(version, scheme string) string {
 	return version
 }
 
+func hasConstraintSyntax(version, scheme string) bool {
+	constraint := strings.TrimSpace(version)
+	if constraint == "" {
+		return false
+	}
+
+	switch constraint[0] {
+	case '<', '>', '=', '!', '^', '~':
+		return true
+	}
+
+	switch scheme {
+	case ecosystemMaven:
+		return constraint[0] == '[' || constraint[0] == '('
+	case "conan":
+		return constraint == "*" || constraint == "*-" ||
+			strings.HasSuffix(constraint, "-") || strings.Contains(constraint, "||") ||
+			strings.Contains(constraint, ",")
+	}
+
+	return false
+}
+
 // BuildPURLString builds a PURL string directly from ecosystem-native identifiers
 // without creating intermediate PURL structs. This is the fast path for manifest
 // parsing where we just need the string output. It returns an empty string when
diff --git a/makepurl_test.go b/makepurl_test.go
index fbf61c8..9d68d81 100644
--- a/makepurl_test.go
+++ b/makepurl_test.go
@@ -25,15 +25,26 @@ func TestCleanVersion(t *testing.T) {
 		{">=1.0.0", "pypi", "1.0.0"},
 		{"~=1.4.2", "pypi", "1.4.2"},
 
+		// maven constraints
+		{"[1.0,2.0)", "maven", "1.0"},
+
 		// cargo constraints
 		{"^1.0.0", "cargo", "1.0.0"},
 
+		// conan constraints
+		{"^1.2.3", "conan", "1.2.3"},
+		{"1.2.3-", "conan", "1.2.3"},
+
 		// Plain versions pass through
+		{"1.0", "composer", "1.0"},
+		{"1.0", "npm", "1.0"},
 		{"1.0.0", "npm", "1.0.0"},
 		{"v1.0.0", "go", "v1.0.0"},
+		{" 1.0 ", "composer", " 1.0 "},
 
-		// Empty
+		// Empty and whitespace-only
 		{"", "npm", ""},
+		{"   ", "npm", "   "},
 	}
 
 	for _, tt := range tests {
@@ -64,6 +75,7 @@ func TestBuildPURLString(t *testing.T) {
 		{"with registry", "npm", "lodash", "1.0.0", "https://npm.example.com", "pkg:npm/lodash@1.0.0?repository_url=https:%2F%2Fnpm.example.com"},
 		{"default registry ignored", "npm", "lodash", "1.0.0", "https://registry.npmjs.org", "pkg:npm/lodash@1.0.0"},
 		{"composer", "packagist", "vendor/pkg", "1.0", "", "pkg:composer/vendor/pkg@1.0"},
+		{"conan range prerelease marker", "conan", "openssl", "1.2.3-", "", "pkg:conan/openssl@1.2.3"},
 		{"composer normalization", "packagist", "Vendor/Package", "1.0", "", "pkg:composer/vendor/package@1.0"},
 		{"pypi normalization", "pypi", "Django_REST", "1.0.0", "", "pkg:pypi/django-rest@1.0.0"},
 		{"golang normalization", "golang", "GitHub.com/Foo/Bar", "v1.0.0", "", "pkg:golang/github.com/foo/bar@v1.0.0"},