diff --git a/internal/worker/json.go b/internal/worker/json.go
index 67642fa70..fa50ef546 100644
--- a/internal/worker/json.go
+++ b/internal/worker/json.go
@@ -183,75 +183,6 @@ type DepsolveJob struct {
 	Releasever       string                        `json:"releasever"`
 }
 
-// Custom marshaller for keeping compatibility with older workers.  The
-// serialised format encompasses both the old and new DepsolveJob formats.  It
-// is meant to be temporarily used to transition from the old to the new
-// format.
-func (ds DepsolveJob) MarshalJSON() ([]byte, error) {
-	// NOTE: Common, top level repositories aren't used because in the new
-	// format they don't exist; putting all required repositories on all
-	// package sets as PackageSetsRepos should produce the same behaviour so
-	// there's no need to try and figure out the "common" ones.
-	// This also makes it possible to use old workers for new image types that
-	// are incompatible with having common repos for all package sets (RHEL 7.9).
-	compatJob := struct {
-		// new format
-		GroupedPackageSets map[string][]rpmmd.PackageSet `json:"grouped_package_sets"`
-		ModulePlatformID   string                        `json:"module_platform_id"`
-		Arch               string                        `json:"arch"`
-		Releasever         string                        `json:"releasever"`
-
-		// old format elements
-		PackageSetsChains map[string][]string           `json:"package_sets_chains"`
-		PackageSets       map[string]rpmmd.PackageSet   `json:"package_sets"`
-		PackageSetsRepos  map[string][]rpmmd.RepoConfig `json:"package_sets_repositories,omitempty"`
-	}{
-		// new format substruct
-		GroupedPackageSets: ds.PackageSets,
-		ModulePlatformID:   ds.ModulePlatformID,
-		Arch:               ds.Arch,
-		Releasever:         ds.Releasever,
-	}
-
-	// build equivalent old format substruct
-	pkgSetRepos := make(map[string][]rpmmd.RepoConfig)
-	pkgSets := make(map[string]rpmmd.PackageSet)
-	chains := make(map[string][]string)
-	for chainName, pkgSetChain := range ds.PackageSets {
-		if len(pkgSetChain) == 1 {
-			// single element "chain" (i.e., not a chain)
-			pkgSets[chainName] = rpmmd.PackageSet{
-				Include: pkgSetChain[0].Include,
-				Exclude: pkgSetChain[0].Exclude,
-			}
-			pkgSetRepos[chainName] = pkgSetChain[0].Repositories
-			continue
-		}
-		chain := make([]string, len(pkgSetChain))
-		for idx, set := range pkgSetChain {
-			// the names of the individual sets in the chain don't matter, as long
-			// as they match the keys for the repo configs
-			setName := fmt.Sprintf("%s-%d", chainName, idx)
-			// the package set (without repos)
-			pkgSets[setName] = rpmmd.PackageSet{
-				Include: set.Include,
-				Exclude: set.Exclude,
-			}
-			// set repositories
-			pkgSetRepos[setName] = set.Repositories
-			// add name to the chain
-			chain[idx] = setName
-		}
-		chains[chainName] = chain
-	}
-
-	compatJob.PackageSets = pkgSets
-	compatJob.PackageSetsChains = chains
-	compatJob.PackageSetsRepos = pkgSetRepos
-
-	return json.Marshal(compatJob)
-}
-
 type ErrorType string
 
 const (