diff --git a/extractor/filesystem/language/python/internal/pypipurl/pythonpurl.go b/extractor/filesystem/language/python/internal/pypipurl/pythonpurl.go
new file mode 100644
index 00000000..9bcf69a2
--- /dev/null
+++ b/extractor/filesystem/language/python/internal/pypipurl/pythonpurl.go
@@ -0,0 +1,22 @@
+// Package pypipurl converts an inventory to a PyPI type PackageURL.
+package pypipurl
+
+import (
+	"strings"
+
+	"github.com/google/osv-scalibr/extractor"
+	"github.com/google/osv-scalibr/purl"
+)
+
+// MakePackageURL returns a package URL following the purl PyPI spec:
+// - Name is lowercased
+// - Replaces _ with -
+//
+// See: https://github.com/package-url/purl-spec/blob/master/PURL-TYPES.rst#pypi
+func MakePackageURL(i *extractor.Inventory) *purl.PackageURL {
+	return &purl.PackageURL{
+		Type:    purl.TypePyPi,
+		Name:    strings.ReplaceAll(strings.ToLower(i.Name), "_", "-"),
+		Version: i.Version,
+	}
+}
diff --git a/extractor/filesystem/language/python/pdmlock/extractor.go b/extractor/filesystem/language/python/pdmlock/extractor.go
index e843f986..93946461 100644
--- a/extractor/filesystem/language/python/pdmlock/extractor.go
+++ b/extractor/filesystem/language/python/pdmlock/extractor.go
@@ -10,6 +10,7 @@ import (
 	"github.com/BurntSushi/toml"
 	"github.com/google/osv-scalibr/extractor"
 	"github.com/google/osv-scalibr/extractor/filesystem"
+	"github.com/google/osv-scalibr/extractor/filesystem/language/python/internal/pypipurl"
 	"github.com/google/osv-scalibr/extractor/filesystem/osv"
 	"github.com/google/osv-scalibr/plugin"
 	"github.com/google/osv-scalibr/purl"
@@ -98,11 +99,7 @@ func (e Extractor) Extract(ctx context.Context, input *filesystem.ScanInput) ([]
 
 // ToPURL converts an inventory created by this extractor into a PURL.
 func (e Extractor) ToPURL(i *extractor.Inventory) (*purl.PackageURL, error) {
-	return &purl.PackageURL{
-		Type:    purl.TypePyPi,
-		Name:    i.Name,
-		Version: i.Version,
-	}, nil
+	return pypipurl.MakePackageURL(i), nil
 }
 
 // ToCPEs is not applicable as this extractor does not infer CPEs from the Inventory.
diff --git a/extractor/filesystem/language/python/pipfilelock/extractor.go b/extractor/filesystem/language/python/pipfilelock/extractor.go
index 5934fc53..5a674aa0 100644
--- a/extractor/filesystem/language/python/pipfilelock/extractor.go
+++ b/extractor/filesystem/language/python/pipfilelock/extractor.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/google/osv-scalibr/extractor"
 	"github.com/google/osv-scalibr/extractor/filesystem"
+	"github.com/google/osv-scalibr/extractor/filesystem/language/python/internal/pypipurl"
 	"github.com/google/osv-scalibr/extractor/filesystem/osv"
 	"github.com/google/osv-scalibr/plugin"
 	"github.com/google/osv-scalibr/purl"
@@ -100,11 +101,7 @@ func addPkgDetails(details map[string]*extractor.Inventory, packages map[string]
 
 // ToPURL converts an inventory created by this extractor into a PURL.
 func (e Extractor) ToPURL(i *extractor.Inventory) (*purl.PackageURL, error) {
-	return &purl.PackageURL{
-		Type:    purl.TypePyPi,
-		Name:    i.Name,
-		Version: i.Version,
-	}, nil
+	return pypipurl.MakePackageURL(i), nil
 }
 
 // ToCPEs is not applicable as this extractor does not infer CPEs from the Inventory.
diff --git a/extractor/filesystem/language/python/poetrylock/extractor.go b/extractor/filesystem/language/python/poetrylock/extractor.go
index 989d7a58..7321452b 100644
--- a/extractor/filesystem/language/python/poetrylock/extractor.go
+++ b/extractor/filesystem/language/python/poetrylock/extractor.go
@@ -10,6 +10,7 @@ import (
 	"github.com/BurntSushi/toml"
 	"github.com/google/osv-scalibr/extractor"
 	"github.com/google/osv-scalibr/extractor/filesystem"
+	"github.com/google/osv-scalibr/extractor/filesystem/language/python/internal/pypipurl"
 	"github.com/google/osv-scalibr/extractor/filesystem/osv"
 	"github.com/google/osv-scalibr/plugin"
 	"github.com/google/osv-scalibr/purl"
@@ -91,11 +92,7 @@ func (e Extractor) Extract(ctx context.Context, input *filesystem.ScanInput) ([]
 
 // ToPURL converts an inventory created by this extractor into a PURL.
 func (e Extractor) ToPURL(i *extractor.Inventory) (*purl.PackageURL, error) {
-	return &purl.PackageURL{
-		Type:    purl.TypePyPi,
-		Name:    i.Name,
-		Version: i.Version,
-	}, nil
+	return pypipurl.MakePackageURL(i), nil
 }
 
 // ToCPEs is not applicable as this extractor does not infer CPEs from the Inventory.
diff --git a/extractor/filesystem/language/python/requirements/extractor.go b/extractor/filesystem/language/python/requirements/extractor.go
index 5e1a77a4..81a6d954 100644
--- a/extractor/filesystem/language/python/requirements/extractor.go
+++ b/extractor/filesystem/language/python/requirements/extractor.go
@@ -28,6 +28,7 @@ import (
 	"github.com/google/osv-scalibr/extractor/filesystem"
 	scalibrfs "github.com/google/osv-scalibr/fs"
 	"github.com/google/osv-scalibr/log"
+	"github.com/google/osv-scalibr/extractor/filesystem/language/python/internal/pypipurl"
 	"github.com/google/osv-scalibr/plugin"
 	"github.com/google/osv-scalibr/purl"
 	"github.com/google/osv-scalibr/stats"
@@ -288,11 +289,7 @@ func splitPerRequirementOptions(s string) (string, []string) {
 
 // ToPURL converts an inventory created by this extractor into a PURL.
 func (e Extractor) ToPURL(i *extractor.Inventory) (*purl.PackageURL, error) {
-	return &purl.PackageURL{
-		Type:    purl.TypePyPi,
-		Name:    strings.ToLower(i.Name),
-		Version: i.Version,
-	}, nil
+	return pypipurl.MakePackageURL(i), nil
 }
 
 // ToCPEs is not applicable as this extractor does not infer CPEs from the Inventory.
diff --git a/extractor/filesystem/language/python/wheelegg/extractor.go b/extractor/filesystem/language/python/wheelegg/extractor.go
index 9ba8284c..f34c2709 100644
--- a/extractor/filesystem/language/python/wheelegg/extractor.go
+++ b/extractor/filesystem/language/python/wheelegg/extractor.go
@@ -31,6 +31,7 @@ import (
 	"github.com/google/osv-scalibr/extractor"
 	"github.com/google/osv-scalibr/extractor/filesystem"
 	"github.com/google/osv-scalibr/extractor/filesystem/internal/units"
+	"github.com/google/osv-scalibr/extractor/filesystem/language/python/internal/pypipurl"
 	"github.com/google/osv-scalibr/plugin"
 	"github.com/google/osv-scalibr/purl"
 	"github.com/google/osv-scalibr/stats"
@@ -265,11 +266,7 @@ func parse(r io.Reader) (*extractor.Inventory, error) {
 
 // ToPURL converts an inventory created by this extractor into a PURL.
 func (e Extractor) ToPURL(i *extractor.Inventory) (*purl.PackageURL, error) {
-	return &purl.PackageURL{
-		Type:    purl.TypePyPi,
-		Name:    strings.ToLower(i.Name),
-		Version: i.Version,
-	}, nil
+	return pypipurl.MakePackageURL(i), nil
 }
 
 // ToCPEs is not applicable as this extractor does not infer CPEs from the Inventory.