diff --git a/pkg/distro/defs/loader.go b/pkg/distro/defs/loader.go
index af14457b25..c56bec0b4e 100644
--- a/pkg/distro/defs/loader.go
+++ b/pkg/distro/defs/loader.go
@@ -240,6 +240,10 @@ func NewDistroYAML(nameVer string) (*DistroYAML, error) {
 			if err := v.runTemplates(foundDistro); err != nil {
 				return nil, err
 			}
+			if err := v.setupDefaultFS(foundDistro.DefaultFSType.String()); err != nil {
+				return nil, err
+			}
+
 			foundDistro.imageTypes[name] = v
 		}
 	}
@@ -462,6 +466,44 @@ func (it *ImageTypeYAML) runTemplates(distro *DistroYAML) error {
 	return nil
 }
 
+func (it *ImageTypeYAML) setupDefaultFS(distroDefaultFS string) error {
+	subs := func(pts map[string]*disk.PartitionTable) error {
+		for _, pt := range pts {
+			err := pt.ForEachMountable(func(mnt disk.Mountable, _ []disk.Entity) error {
+				elem, ok := mnt.(*disk.Filesystem)
+				if !ok {
+					return nil
+				}
+				if elem.Type == "" {
+					if distroDefaultFS == "" {
+						return fmt.Errorf("mount %q requires a default filesystem for the distribution but none set", mnt.GetMountpoint())
+					}
+					elem.Type = distroDefaultFS
+				}
+				return nil
+			})
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+	// we need to update both the partition tables and all
+	// partition tables overrides
+	if err := subs(it.PartitionTables); err != nil {
+		return err
+	}
+	if it.PartitionTablesOverrides != nil {
+		for _, cond := range it.PartitionTablesOverrides.Conditions {
+			if err := subs(cond.Override); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
 type platformsOverride struct {
 	Conditions map[string]*conditionsPlatforms `yaml:"conditions,omitempty"`
 }
diff --git a/pkg/distro/defs/loader_test.go b/pkg/distro/defs/loader_test.go
index 10c1c6b24d..f6f50e681e 100644
--- a/pkg/distro/defs/loader_test.go
+++ b/pkg/distro/defs/loader_test.go
@@ -315,6 +315,127 @@ image_types:
 	}, partTable)
 }
 
+func TestDefsPartitionTableFilesystemDistroDefault(t *testing.T) {
+	fakeDistrosYaml := `
+distros:
+  - name: test-distro-1
+    defs_path: test-distro
+    default_fs_type: ext4
+`
+	fakeImageTypesYaml := `
+image_types:
+  test_type:
+    filename: test.img
+    platforms:
+      - arch: x86_64
+    partition_table:
+      test_arch:
+        partitions:
+          - payload_type: filesystem
+            payload:
+              # note that no "type: <fstype>" is set here
+              mountpoint: "/"
+`
+	baseDir := makeFakeDistrosYAML(t, fakeDistrosYaml, fakeImageTypesYaml)
+	restore := defs.MockDataFS(baseDir)
+	defer restore()
+	td, err := defs.NewDistroYAML("test-distro-1")
+	require.NoError(t, err)
+	it := td.ImageTypes()["test_type"]
+	require.NotNil(t, it)
+
+	partTable, err := it.PartitionTable(distro.ID{Name: "test-distro", MajorVersion: 1}, "test_arch")
+	require.NoError(t, err)
+	assert.Equal(t, &disk.PartitionTable{
+		Partitions: []disk.Partition{
+			{
+				Payload: &disk.Filesystem{
+					Type:       "ext4",
+					Mountpoint: "/",
+				},
+			},
+		},
+	}, partTable)
+}
+
+func TestDefsPartitionTableFilesystemPartTableOverride(t *testing.T) {
+	fakeDistrosYaml := `
+distros:
+  - name: test-distro-1
+    defs_path: test-distro
+    default_fs_type: ext4
+`
+	fakeImageTypesYaml := `
+image_types:
+  test_type:
+    filename: test.img
+    platforms:
+      - arch: x86_64
+    partition_table:
+      x86_64:
+        partitions:
+    partition_tables_override:
+      conditions:
+        "test condition":
+          when:
+            distro_name: test-distro
+          override:
+            x86_64:
+              partitions:
+                - payload_type: filesystem
+                  payload:
+                    # note that no "type: <fstype>" is set here
+                    mountpoint: "/"
+`
+	baseDir := makeFakeDistrosYAML(t, fakeDistrosYaml, fakeImageTypesYaml)
+	restore := defs.MockDataFS(baseDir)
+	defer restore()
+	td, err := defs.NewDistroYAML("test-distro-1")
+	require.NoError(t, err)
+	it := td.ImageTypes()["test_type"]
+	require.NotNil(t, it)
+
+	partTable, err := it.PartitionTable(distro.ID{Name: "test-distro", MajorVersion: 1}, "x86_64")
+	require.NoError(t, err)
+	assert.Equal(t, &disk.PartitionTable{
+		Partitions: []disk.Partition{
+			{
+				Payload: &disk.Filesystem{
+					Type:       "ext4",
+					Mountpoint: "/",
+				},
+			},
+		},
+	}, partTable)
+}
+
+func TestDefsPartitionTableFilesystemDistroDefaultErr(t *testing.T) {
+	fakeDistrosYaml := `
+distros:
+  - name: test-distro-1
+    defs_path: test-distro
+`
+	fakeImageTypesYaml := `
+image_types:
+  test_type:
+    filename: test.img
+    platforms:
+      - arch: x86_64
+    partition_table:
+      test_arch:
+        partitions:
+          - payload_type: filesystem
+            payload:
+              # note that no "type: <fstype>" is set here
+              mountpoint: "/"
+`
+	baseDir := makeFakeDistrosYAML(t, fakeDistrosYaml, fakeImageTypesYaml)
+	restore := defs.MockDataFS(baseDir)
+	defer restore()
+	_, err := defs.NewDistroYAML("test-distro-1")
+	assert.EqualError(t, err, `mount "/" requires a default filesystem for the distribution but none set`)
+}
+
 var fakeImageTypesYaml = `
 image_types:
   test_type: