diff --git a/pkg/dependency/parser/python/poetry/parse.go b/pkg/dependency/parser/python/poetry/parse.go
index e691a0cb2532..8b06942d3b6b 100644
--- a/pkg/dependency/parser/python/poetry/parse.go
+++ b/pkg/dependency/parser/python/poetry/parse.go
@@ -105,7 +105,7 @@ func (p *Parser) parseDependencies(deps map[string]any, pkgVersions map[string][
 }
 
 func (p *Parser) parseDependency(name string, versRange any, pkgVersions map[string][]string) (string, error) {
-	name = normalizePkgName(name)
+	name = NormalizePkgName(name)
 	vers, ok := pkgVersions[name]
 	if !ok {
 		return "", xerrors.Errorf("no version found for %q", name)
@@ -149,9 +149,11 @@ func matchVersion(currentVersion, constraint string) (bool, error) {
 	return c.Check(v), nil
 }
 
-func normalizePkgName(name string) string {
+// NormalizePkgName normalizes the package name based on pep-0426
+func NormalizePkgName(name string) string {
 	// The package names don't use `_`, `.` or upper case, but dependency names can contain them.
 	// We need to normalize those names.
+	// cf. https://peps.python.org/pep-0426/#name
 	name = strings.ToLower(name)              // e.g. https://github.com/python-poetry/poetry/blob/c8945eb110aeda611cc6721565d7ad0c657d453a/poetry.lock#L819
 	name = strings.ReplaceAll(name, "_", "-") // e.g. https://github.com/python-poetry/poetry/blob/c8945eb110aeda611cc6721565d7ad0c657d453a/poetry.lock#L50
 	name = strings.ReplaceAll(name, ".", "-") // e.g. https://github.com/python-poetry/poetry/blob/c8945eb110aeda611cc6721565d7ad0c657d453a/poetry.lock#L816
diff --git a/pkg/fanal/analyzer/language/python/poetry/poetry.go b/pkg/fanal/analyzer/language/python/poetry/poetry.go
index 600f53bafc92..b16ba88481c5 100644
--- a/pkg/fanal/analyzer/language/python/poetry/poetry.go
+++ b/pkg/fanal/analyzer/language/python/poetry/poetry.go
@@ -8,6 +8,7 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/samber/lo"
 	"golang.org/x/xerrors"
 
 	"github.com/aquasecurity/trivy/pkg/dependency/parser/python/poetry"
@@ -102,8 +103,8 @@ func (a poetryAnalyzer) mergePyProject(fsys fs.FS, dir string, app *types.Applic
 		return xerrors.Errorf("unable to parse %s: %w", path, err)
 	}
 
+	// Identify the direct/transitive dependencies
 	for i, pkg := range app.Packages {
-		// Identify the direct/transitive dependencies
 		if _, ok := p[pkg.Name]; ok {
 			app.Packages[i].Relationship = types.RelationshipDirect
 		} else {
@@ -127,5 +128,11 @@ func (a poetryAnalyzer) parsePyProject(fsys fs.FS, path string) (map[string]any,
 	if err != nil {
 		return nil, err
 	}
+
+	// Packages from `pyproject.toml` can use uppercase characters, `.` and `_`.
+	parsed = lo.MapKeys(parsed, func(_ any, pkgName string) string {
+		return poetry.NormalizePkgName(pkgName)
+	})
+
 	return parsed, nil
 }
diff --git a/pkg/fanal/analyzer/language/python/poetry/testdata/happy/pyproject.toml b/pkg/fanal/analyzer/language/python/poetry/testdata/happy/pyproject.toml
index 2df330973ff2..9d23492736e4 100644
--- a/pkg/fanal/analyzer/language/python/poetry/testdata/happy/pyproject.toml
+++ b/pkg/fanal/analyzer/language/python/poetry/testdata/happy/pyproject.toml
@@ -6,7 +6,7 @@ authors = ["Trivy"]
 
 [tool.poetry.dependencies]
 python = "^3.9"
-flask = "^1.0"
+Flask = "^1.0"
 requests = {version = "2.28.1", optional = true}
 
 [tool.poetry.dev-dependencies]