diff --git a/internal/setup/setup_test.go b/internal/setup/setup_test.go
index ec61490b..2bda79c5 100644
--- a/internal/setup/setup_test.go
+++ b/internal/setup/setup_test.go
@@ -878,6 +878,18 @@ var setupTests = []setupTest{{
 		`,
 	},
 	relerror: `slice mypkg_myslice mutable is not a regular file: /path`,
+}, {
+	summary: "Mutable path cannot have 'until' set to mutate",
+	input: map[string]string{
+		"slices/mydir/mypkg.yaml": `
+			package: mypkg
+			slices:
+				myslice:
+					contents:
+						/path: {text: data, mutable: true, until: mutate}
+		`,
+	},
+	relerror: `slice mypkg_myslice cannot have both 'mutable' and 'until: mutate' for path /path`,
 }, {
 	summary: "Until checks its value for validity",
 	input: map[string]string{
diff --git a/internal/setup/yaml.go b/internal/setup/yaml.go
index 1760f1b4..2ebbf352 100644
--- a/internal/setup/yaml.go
+++ b/internal/setup/yaml.go
@@ -666,6 +666,9 @@ func parsePackage(release *Release, pkgName, pkgPath string, data []byte) (*Pack
 			if mutable && kinds[0] != TextPath && (kinds[0] != CopyPath || isDir) {
 				return nil, fmt.Errorf("slice %s_%s mutable is not a regular file: %s", pkg.Name, sliceName, contPath)
 			}
+			if mutable && until == UntilMutate {
+				return nil, fmt.Errorf("slice %s_%s cannot have both 'mutable' and 'until: mutate' for path %s", pkg.Name, sliceName, contPath)
+			}
 			slice.Contents[contPath] = PathInfo{
 				Kind:     kinds[0],
 				Info:     info,