diff --git a/internal/manifest/manifest.go b/internal/manifest/manifest.go
index fd8f1d3c..724e4d2e 100644
--- a/internal/manifest/manifest.go
+++ b/internal/manifest/manifest.go
@@ -3,7 +3,9 @@ package manifest
 import (
 	"fmt"
 	"io"
+	"path/filepath"
 	"slices"
+	"strings"
 
 	"github.com/canonical/chisel/internal/jsonwall"
 	"github.com/canonical/chisel/internal/setup"
@@ -158,6 +160,22 @@ func Validate(manifest *Manifest) (err error) {
 	return nil
 }
 
+// LocateManifestSlices finds the paths marked with "generate:manifest" and
+// returns a map from the manifest path to all the slices that declare it.
+func LocateManifestSlices(slices []*setup.Slice, manifestFileName string) map[string][]*setup.Slice {
+	manifestSlices := make(map[string][]*setup.Slice)
+	for _, slice := range slices {
+		for path, info := range slice.Contents {
+			if info.Generate == setup.GenerateManifest {
+				dir := strings.TrimSuffix(path, "**")
+				path = filepath.Join(dir, manifestFileName)
+				manifestSlices[path] = append(manifestSlices[path], slice)
+			}
+		}
+	}
+	return manifestSlices
+}
+
 type prefixable interface {
 	Path | Content | Package | Slice
 }
diff --git a/internal/manifest/manifest_test.go b/internal/manifest/manifest_test.go
index 1da510da..0731f40e 100644
--- a/internal/manifest/manifest_test.go
+++ b/internal/manifest/manifest_test.go
@@ -9,8 +9,12 @@ import (
 	. "gopkg.in/check.v1"
 
 	"github.com/canonical/chisel/internal/manifest"
+	"github.com/canonical/chisel/internal/setup"
+	"github.com/canonical/chisel/internal/testutil"
 )
 
+var testKey = testutil.PGPKeys["key1"]
+
 type manifestContents struct {
 	Paths    []*manifest.Path
 	Packages []*manifest.Package
@@ -123,7 +127,7 @@ var manifestTests = []struct {
 	readError: `cannot read manifest: unknown schema version "2.0"`,
 }}
 
-func (s *S) TestRun(c *C) {
+func (s *S) TestManifestReadValidate(c *C) {
 	for _, test := range manifestTests {
 		c.Logf("Summary: %s", test.summary)
 
@@ -169,6 +173,102 @@ func (s *S) TestRun(c *C) {
 	}
 }
 
+var locateManifestSlicesTests = []struct {
+	summary  string
+	slices   []*setup.Slice
+	filename string
+	expected map[string][]string
+}{{
+	summary: "Single slice",
+	slices: []*setup.Slice{{
+		Name: "slice1",
+		Contents: map[string]setup.PathInfo{
+			"/folder/**": {
+				Kind:     "generate",
+				Generate: "manifest",
+			},
+		},
+	}},
+	filename: "manifest.wall",
+	expected: map[string][]string{
+		"/folder/manifest.wall": []string{"slice1"},
+	},
+}, {
+	summary: "No slice matched",
+	slices: []*setup.Slice{{
+		Name:     "slice1",
+		Contents: map[string]setup.PathInfo{},
+	}},
+	filename: "manifest.wall",
+	expected: map[string][]string{},
+}, {
+	summary: "Several matches with several groups",
+	slices: []*setup.Slice{{
+		Name: "slice1",
+		Contents: map[string]setup.PathInfo{
+			"/folder/**": {
+				Kind:     "generate",
+				Generate: "manifest",
+			},
+		},
+	}, {
+		Name: "slice2",
+		Contents: map[string]setup.PathInfo{
+			"/folder/**": {
+				Kind:     "generate",
+				Generate: "manifest",
+			},
+		},
+	}, {
+		Name:     "slice3",
+		Contents: map[string]setup.PathInfo{},
+	}, {
+		Name: "slice4",
+		Contents: map[string]setup.PathInfo{
+			"/other-folder/**": {
+				Kind:     "generate",
+				Generate: "manifest",
+			},
+		},
+	}, {
+		Name: "slice5",
+		Contents: map[string]setup.PathInfo{
+			"/other-folder/**": {
+				Kind:     "generate",
+				Generate: "manifest",
+			},
+		},
+	}},
+	filename: "mfest.wall",
+	expected: map[string][]string{
+		"/folder/mfest.wall":       {"slice1", "slice2"},
+		"/other-folder/mfest.wall": {"slice4", "slice5"},
+	},
+}}
+
+func (s *S) TestLocateManifestSlices(c *C) {
+	for _, test := range locateManifestSlicesTests {
+		c.Logf("Summary: %s", test.summary)
+
+		manifestSlices := manifest.LocateManifestSlices(test.slices, test.filename)
+
+		slicesByName := map[string]*setup.Slice{}
+		for _, slice := range test.slices {
+			_, ok := slicesByName[slice.Name]
+			c.Assert(ok, Equals, false, Commentf("duplicated slice name"))
+			slicesByName[slice.Name] = slice
+		}
+
+		c.Assert(manifestSlices, HasLen, len(test.expected))
+		for path, slices := range manifestSlices {
+			c.Assert(slices, HasLen, len(test.expected[path]))
+			for i, sliceName := range test.expected[path] {
+				c.Assert(slicesByName[sliceName], DeepEquals, slices[i])
+			}
+		}
+	}
+}
+
 func dumpManifestContents(c *C, mfest *manifest.Manifest) *manifestContents {
 	var slices []*manifest.Slice
 	err := mfest.IterateSlices("", func(slice *manifest.Slice) error {
diff --git a/internal/slicer/slicer.go b/internal/slicer/slicer.go
index aada5417..0b2af526 100644
--- a/internal/slicer/slicer.go
+++ b/internal/slicer/slicer.go
@@ -439,10 +439,7 @@ type generateManifestsOptions struct {
 }
 
 func generateManifests(options *generateManifestsOptions) error {
-	manifestSlices, err := locateManifestSlices(options.selection)
-	if err != nil {
-		return err
-	}
+	manifestSlices := manifest.LocateManifestSlices(options.selection, manifestFileName)
 	if len(manifestSlices) == 0 {
 		// Nothing to do.
 		return nil
@@ -451,7 +448,7 @@ func generateManifests(options *generateManifestsOptions) error {
 		Schema: manifest.Schema,
 	})
 
-	err = manifestAddPackages(dbw, options.packageInfo)
+	err := manifestAddPackages(dbw, options.packageInfo)
 	if err != nil {
 		return err
 	}
@@ -590,19 +587,3 @@ func unixPerm(mode fs.FileMode) (perm uint32) {
 	}
 	return perm
 }
-
-// locateManifestSlices finds the paths marked with "generate:manifest" and
-// returns a map from the manifest path to all the slices that declare it.
-func locateManifestSlices(slices []*setup.Slice) (map[string][]*setup.Slice, error) {
-	manifestSlices := make(map[string][]*setup.Slice)
-	for _, slice := range slices {
-		for path, info := range slice.Contents {
-			if info.Generate == setup.GenerateManifest {
-				dir := strings.TrimSuffix(path, "**")
-				path = filepath.Join(dir, manifestFileName)
-				manifestSlices[path] = append(manifestSlices[path], slice)
-			}
-		}
-	}
-	return manifestSlices, nil
-}