diff --git a/bake/bake.go b/bake/bake.go
index c810933a..5f931572 100644
--- a/bake/bake.go
+++ b/bake/bake.go
@@ -134,7 +134,7 @@ func ReadTargets(ctx context.Context, files []File, targets, overrides []string,
 				gt = append(gt, target)
 			}
 		}
-		g = []*Group{{Targets: dedupString(gt)}}
+		g = []*Group{{Targets: dedupSlice(gt)}}
 	}
 
 	for name, t := range m {
@@ -146,7 +146,7 @@ func ReadTargets(ctx context.Context, files []File, targets, overrides []string,
 	return m, g, nil
 }
 
-func dedupString(s []string) []string {
+func dedupSlice(s []string) []string {
 	if len(s) == 0 {
 		return s
 	}
@@ -161,6 +161,24 @@ func dedupString(s []string) []string {
 	return res
 }
 
+func dedupMap(ms ...map[string]string) map[string]string {
+	if len(ms) == 0 {
+		return nil
+	}
+	res := map[string]string{}
+	for _, m := range ms {
+		if len(m) == 0 {
+			continue
+		}
+		for k, v := range m {
+			if _, ok := res[k]; !ok {
+				res[k] = v
+			}
+		}
+	}
+	return res
+}
+
 func ParseFiles(files []File, defaults map[string]string) (_ *Config, err error) {
 	defer func() {
 		err = formatHCLError(err, files)
@@ -418,7 +436,7 @@ func (c Config) newOverrides(v []string) (map[string]map[string]Override, error)
 }
 
 func (c Config) ResolveGroup(name string) []string {
-	return dedupString(c.group(name, map[string][]string{}))
+	return dedupSlice(c.group(name, map[string][]string{}))
 }
 
 func (c Config) group(name string, visited map[string][]string) []string {
diff --git a/bake/compose.go b/bake/compose.go
index d7476256..1f0a3b5d 100644
--- a/bake/compose.go
+++ b/bake/compose.go
@@ -151,10 +151,12 @@ type xbake struct {
 	Pull          *bool       `yaml:"pull,omitempty"`
 	NoCache       *bool       `yaml:"no-cache,omitempty"`
 	NoCacheFilter stringArray `yaml:"no-cache-filter,omitempty"`
+	Contexts      stringMap   `yaml:"contexts,omitempty"`
 	// don't forget to update documentation if you add a new field:
 	// docs/guides/bake/compose-file.md#extension-field-with-x-bake
 }
 
+type stringMap map[string]string
 type stringArray []string
 
 func (sa *stringArray) UnmarshalYAML(unmarshal func(interface{}) error) error {
@@ -188,25 +190,25 @@ func (t *Target) composeExtTarget(exts map[string]interface{}) error {
 	}
 
 	if len(xb.Tags) > 0 {
-		t.Tags = dedupString(append(t.Tags, xb.Tags...))
+		t.Tags = dedupSlice(append(t.Tags, xb.Tags...))
 	}
 	if len(xb.CacheFrom) > 0 {
-		t.CacheFrom = dedupString(append(t.CacheFrom, xb.CacheFrom...))
+		t.CacheFrom = dedupSlice(append(t.CacheFrom, xb.CacheFrom...))
 	}
 	if len(xb.CacheTo) > 0 {
-		t.CacheTo = dedupString(append(t.CacheTo, xb.CacheTo...))
+		t.CacheTo = dedupSlice(append(t.CacheTo, xb.CacheTo...))
 	}
 	if len(xb.Secrets) > 0 {
-		t.Secrets = dedupString(append(t.Secrets, xb.Secrets...))
+		t.Secrets = dedupSlice(append(t.Secrets, xb.Secrets...))
 	}
 	if len(xb.SSH) > 0 {
-		t.SSH = dedupString(append(t.SSH, xb.SSH...))
+		t.SSH = dedupSlice(append(t.SSH, xb.SSH...))
 	}
 	if len(xb.Platforms) > 0 {
-		t.Platforms = dedupString(append(t.Platforms, xb.Platforms...))
+		t.Platforms = dedupSlice(append(t.Platforms, xb.Platforms...))
 	}
 	if len(xb.Outputs) > 0 {
-		t.Outputs = dedupString(append(t.Outputs, xb.Outputs...))
+		t.Outputs = dedupSlice(append(t.Outputs, xb.Outputs...))
 	}
 	if xb.Pull != nil {
 		t.Pull = xb.Pull
@@ -215,7 +217,10 @@ func (t *Target) composeExtTarget(exts map[string]interface{}) error {
 		t.NoCache = xb.NoCache
 	}
 	if len(xb.NoCacheFilter) > 0 {
-		t.NoCacheFilter = dedupString(append(t.NoCacheFilter, xb.NoCacheFilter...))
+		t.NoCacheFilter = dedupSlice(append(t.NoCacheFilter, xb.NoCacheFilter...))
+	}
+	if len(xb.Contexts) > 0 {
+		t.Contexts = dedupMap(t.Contexts, xb.Contexts)
 	}
 
 	return nil
diff --git a/bake/compose_test.go b/bake/compose_test.go
index 15bbfa7f..4f370c29 100644
--- a/bake/compose_test.go
+++ b/bake/compose_test.go
@@ -267,6 +267,8 @@ services:
         CT_ECR: foo
         CT_TAG: bar
       x-bake:
+        contexts:
+          alpine: docker-image://alpine:3.13
         tags:
           - ct-addon:foo
           - ct-addon:alp
@@ -308,6 +310,7 @@ services:
 	require.Equal(t, c.Targets[0].CacheFrom, []string{"user/app:cache", "type=local,src=path/to/cache"})
 	require.Equal(t, c.Targets[0].CacheTo, []string{"user/app:cache", "type=local,dest=path/to/cache"})
 	require.Equal(t, c.Targets[0].Pull, newBool(true))
+	require.Equal(t, c.Targets[0].Contexts, map[string]string{"alpine": "docker-image://alpine:3.13"})
 	require.Equal(t, c.Targets[1].Tags, []string{"ct-fake-aws:bar"})
 	require.Equal(t, c.Targets[1].Secrets, []string{"id=mysecret,src=/local/secret", "id=mysecret2,src=/local/secret2"})
 	require.Equal(t, c.Targets[1].SSH, []string{"default"})
diff --git a/docs/guides/bake/compose-file.md b/docs/guides/bake/compose-file.md
index 5086de6c..5d40a8c7 100644
--- a/docs/guides/bake/compose-file.md
+++ b/docs/guides/bake/compose-file.md
@@ -209,6 +209,7 @@ Complete list of valid fields for `x-bake`:
 
 * `cache-from`
 * `cache-to`
+* `contexts`
 * `no-cache`
 * `no-cache-filter`
 * `output`