diff --git a/platforms.go b/platforms.go
index 53e729f..54d5bc7 100644
--- a/platforms.go
+++ b/platforms.go
@@ -111,6 +111,7 @@ package platforms
 
 import (
 	"fmt"
+	"net/url"
 	"path"
 	"regexp"
 	"runtime"
@@ -123,7 +124,7 @@ import (
 
 var (
 	specifierRe = regexp.MustCompile(`^[A-Za-z0-9_.-]+$`)
-	osRe        = regexp.MustCompile(`^([A-Za-z0-9_-]+)(?:\(([A-Za-z0-9_.-]*)((?:\+[A-Za-z0-9_.-]+)*)\))?$`)
+	osRe        = regexp.MustCompile(`^([A-Za-z0-9_-]+)(?:\(([A-Za-z0-9_.%-]*)((?:\+[A-Za-z0-9_.%-]+)*)\))?$`)
 )
 
 // Platform is a type alias for convenience, so there is no need to import image-spec package everywhere.
@@ -240,9 +241,20 @@ func Parse(specifier string) (specs.Platform, error) {
 			}
 
 			p.OS = normalizeOS(osOptions[1])
-			p.OSVersion = osOptions[2]
+			osVersion, err := decodeOSOption(osOptions[2])
+			if err != nil {
+				return specs.Platform{}, fmt.Errorf("%q has an invalid OS version %q: %w", specifier, osOptions[2], err)
+			}
+			p.OSVersion = osVersion
 			if osOptions[3] != "" {
-				p.OSFeatures = strings.Split(osOptions[3][1:], "+")
+				rawFeatures := strings.Split(osOptions[3][1:], "+")
+				p.OSFeatures = make([]string, len(rawFeatures))
+				for i, f := range rawFeatures {
+					p.OSFeatures[i], err = decodeOSOption(f)
+					if err != nil {
+						return specs.Platform{}, fmt.Errorf("%q has an invalid OS feature %q: %w", specifier, f, err)
+					}
+				}
 			}
 		} else {
 			if !specifierRe.MatchString(part) {
@@ -327,14 +339,14 @@ func FormatAll(platform specs.Platform) string {
 		return "unknown"
 	}
 
-	osOptions := platform.OSVersion
+	osOptions := encodeOSOption(platform.OSVersion)
 	features := platform.OSFeatures
 	if !slices.IsSorted(features) {
 		features = slices.Clone(features)
 		slices.Sort(features)
 	}
-	if len(features) > 0 {
-		osOptions += "+" + strings.Join(features, "+")
+	for _, f := range features {
+		osOptions += "+" + encodeOSOption(f)
 	}
 	if osOptions != "" {
 		OSAndVersion := fmt.Sprintf("%s(%s)", platform.OS, osOptions)
@@ -343,6 +355,28 @@ func FormatAll(platform specs.Platform) string {
 	return path.Join(platform.OS, platform.Architecture, platform.Variant)
 }
 
+// osOptionReplacer encodes characters in OS option values (version and
+// features) that are ambiguous with the format syntax. The percent sign
+// must be replaced first to avoid double-encoding.
+var osOptionReplacer = strings.NewReplacer(
+	"%", "%25",
+	"+", "%2B",
+	"(", "%28",
+	")", "%29",
+	"/", "%2F",
+)
+
+func encodeOSOption(v string) string {
+	return osOptionReplacer.Replace(v)
+}
+
+func decodeOSOption(v string) (string, error) {
+	if strings.Contains(v, "%") {
+		return url.PathUnescape(v)
+	}
+	return v, nil
+}
+
 // Normalize validates and translate the platform to the canonical value.
 //
 // For example, if "Aarch64" is encountered, we change it to "arm64" or if
diff --git a/platforms_test.go b/platforms_test.go
index c9e8326..dddecb8 100644
--- a/platforms_test.go
+++ b/platforms_test.go
@@ -391,6 +391,40 @@ func TestParseSelector(t *testing.T) {
 			formatted:   path.Join("linux(+erofs+unsorted)", defaultArch, defaultVariant),
 			useV2Format: true,
 		},
+		{
+			input: "windows(10.0.17763%2Bbuild.42)",
+			expected: specs.Platform{
+				OS:           "windows",
+				OSVersion:    "10.0.17763+build.42",
+				Architecture: defaultArch,
+				Variant:      defaultVariant,
+			},
+			formatted:   path.Join("windows(10.0.17763%2Bbuild.42)", defaultArch, defaultVariant),
+			useV2Format: true,
+		},
+		{
+			input: "windows(10.0.17763%2Bbuild.42+win32k)",
+			expected: specs.Platform{
+				OS:           "windows",
+				OSVersion:    "10.0.17763+build.42",
+				OSFeatures:   []string{"win32k"},
+				Architecture: defaultArch,
+				Variant:      defaultVariant,
+			},
+			formatted:   path.Join("windows(10.0.17763%2Bbuild.42+win32k)", defaultArch, defaultVariant),
+			useV2Format: true,
+		},
+		{
+			input: "windows(50%25done)",
+			expected: specs.Platform{
+				OS:           "windows",
+				OSVersion:    "50%done",
+				Architecture: defaultArch,
+				Variant:      defaultVariant,
+			},
+			formatted:   path.Join("windows(50%25done)", defaultArch, defaultVariant),
+			useV2Format: true,
+		},
 	} {
 		t.Run(testcase.input, func(t *testing.T) {
 			if testcase.skip {
@@ -446,6 +480,73 @@ func TestParseSelector(t *testing.T) {
 	}
 }
 
+func TestFormatAllEncoding(t *testing.T) {
+	for _, testcase := range []struct {
+		platform specs.Platform
+		expected string
+	}{
+		{
+			platform: specs.Platform{OS: "windows", OSVersion: "10.0.17763+build.42", Architecture: "amd64"},
+			expected: "windows(10.0.17763%2Bbuild.42)/amd64",
+		},
+		{
+			platform: specs.Platform{OS: "windows", OSVersion: "10.0.17763+build.42", OSFeatures: []string{"win32k"}, Architecture: "amd64"},
+			expected: "windows(10.0.17763%2Bbuild.42+win32k)/amd64",
+		},
+		{
+			platform: specs.Platform{OS: "windows", OSVersion: "50%done", Architecture: "amd64"},
+			expected: "windows(50%25done)/amd64",
+		},
+		{
+			platform: specs.Platform{OS: "windows", OSVersion: "1.0(beta)", Architecture: "amd64"},
+			expected: "windows(1.0%28beta%29)/amd64",
+		},
+		{
+			platform: specs.Platform{OS: "windows", OSVersion: "a/b", Architecture: "amd64"},
+			expected: "windows(a%2Fb)/amd64",
+		},
+		{
+			// no special characters, no encoding needed
+			platform: specs.Platform{OS: "windows", OSVersion: "10.0.17763", Architecture: "amd64"},
+			expected: "windows(10.0.17763)/amd64",
+		},
+		{
+			// feature with + in the name
+			platform: specs.Platform{OS: "linux", OSFeatures: []string{"feat+v2"}, Architecture: "amd64"},
+			expected: "linux(+feat%2Bv2)/amd64",
+		},
+		{
+			// feature with % in the name
+			platform: specs.Platform{OS: "linux", OSFeatures: []string{"100%gpu"}, Architecture: "amd64"},
+			expected: "linux(+100%25gpu)/amd64",
+		},
+		{
+			// version and feature both with special characters
+			platform: specs.Platform{OS: "windows", OSVersion: "10.0+build", OSFeatures: []string{"feat+1"}, Architecture: "amd64"},
+			expected: "windows(10.0%2Bbuild+feat%2B1)/amd64",
+		},
+	} {
+		t.Run(testcase.expected, func(t *testing.T) {
+			formatted := FormatAll(testcase.platform)
+			if formatted != testcase.expected {
+				t.Fatalf("unexpected format: %q != %q", formatted, testcase.expected)
+			}
+
+			// verify round-trip
+			reparsed, err := Parse(formatted)
+			if err != nil {
+				t.Fatalf("error parsing formatted output: %v", err)
+			}
+			if reparsed.OSVersion != testcase.platform.OSVersion {
+				t.Fatalf("OSVersion did not survive round trip: %q != %q", reparsed.OSVersion, testcase.platform.OSVersion)
+			}
+			if !reflect.DeepEqual(reparsed.OSFeatures, testcase.platform.OSFeatures) {
+				t.Fatalf("OSFeatures did not survive round trip: %v != %v", reparsed.OSFeatures, testcase.platform.OSFeatures)
+			}
+		})
+	}
+}
+
 func TestParseSelectorInvalid(t *testing.T) {
 	for _, testcase := range []struct {
 		input string