diff --git a/internal/apijson/decoder.go b/internal/apijson/decoder.go
index 68b7ed6..bf01bf6 100644
--- a/internal/apijson/decoder.go
+++ b/internal/apijson/decoder.go
@@ -224,7 +224,7 @@ func (d *decoderBuilder) newUnionDecoder(t reflect.Type) decoderFunc {
 			}
 
 			if len(unionEntry.discriminatorKey) != 0 {
-				discriminatorValue := n.Get(unionEntry.discriminatorKey).Value()
+				discriminatorValue := n.Get(EscapeSJSONKey(unionEntry.discriminatorKey)).Value()
 				if discriminatorValue == variant.DiscriminatorValue {
 					inner := reflect.New(variant.Type).Elem()
 					err := decoder(n, inner, state)
diff --git a/internal/apijson/encoder.go b/internal/apijson/encoder.go
index 0e5f89e..66b319b 100644
--- a/internal/apijson/encoder.go
+++ b/internal/apijson/encoder.go
@@ -18,6 +18,10 @@ import (
 
 var encoders sync.Map // map[encoderEntry]encoderFunc
 
+// If we want to set a literal key value into JSON using sjson, we need to make sure it doesn't have
+// special characters that sjson interprets as a path.
+var EscapeSJSONKey = strings.NewReplacer("\\", "\\\\", "|", "\\|", "#", "\\#", "@", "\\@", "*", "\\*", ".", "\\.", ":", "\\:", "?", "\\?").Replace
+
 func Marshal(value interface{}) ([]byte, error) {
 	e := &encoder{dateFormat: time.RFC3339}
 	return e.marshal(value)
@@ -276,7 +280,7 @@ func (e *encoder) newStructTypeEncoder(t reflect.Type) encoderFunc {
 			if encoded == nil {
 				continue
 			}
-			json, err = sjson.SetRawBytes(json, ef.tag.name, encoded)
+			json, err = sjson.SetRawBytes(json, EscapeSJSONKey(ef.tag.name), encoded)
 			if err != nil {
 				return nil, err
 			}
@@ -354,7 +358,7 @@ func (e *encoder) encodeMapEntries(json []byte, v reflect.Value) ([]byte, error)
 			}
 			encodedKeyString = string(encodedKeyBytes)
 		}
-		encodedKey := []byte(sjsonReplacer.Replace(encodedKeyString))
+		encodedKey := []byte(encodedKeyString)
 		pairs = append(pairs, mapPair{key: encodedKey, value: iter.Value()})
 	}
 
@@ -372,7 +376,7 @@ func (e *encoder) encodeMapEntries(json []byte, v reflect.Value) ([]byte, error)
 		if len(encodedValue) == 0 {
 			continue
 		}
-		json, err = sjson.SetRawBytes(json, string(p.key), encodedValue)
+		json, err = sjson.SetRawBytes(json, EscapeSJSONKey(string(p.key)), encodedValue)
 		if err != nil {
 			return nil, err
 		}
@@ -392,7 +396,3 @@ func (e *encoder) newMapEncoder(t reflect.Type) encoderFunc {
 		return json, nil
 	}
 }
-
-// If we want to set a literal key value into JSON using sjson, we need to make sure it doesn't have
-// special characters that sjson interprets as a path.
-var sjsonReplacer *strings.Replacer = strings.NewReplacer(".", "\\.", ":", "\\:", "*", "\\*")
diff --git a/internal/apijson/json_test.go b/internal/apijson/json_test.go
index e656344..d4c6283 100644
--- a/internal/apijson/json_test.go
+++ b/internal/apijson/json_test.go
@@ -362,7 +362,7 @@ var tests = map[string]struct {
 	"date_time_nano_missing_t_coerce":         {`"2007-03-01 13:03:05.123456789Z"`, time.Date(2007, time.March, 1, 13, 3, 5, 123456789, time.UTC)},
 
 	"map_string":                       {`{"foo":"bar"}`, map[string]string{"foo": "bar"}},
-	"map_string_with_sjson_path_chars": {`{":a.b.c*:d*-1e.f":"bar"}`, map[string]string{":a.b.c*:d*-1e.f": "bar"}},
+	"map_string_with_sjson_path_chars": {`{":a.b.c*:d*-1e.f@g?h":"bar"}`, map[string]string{":a.b.c*:d*-1e.f@g?h": "bar"}},
 	"map_interface":                    {`{"a":1,"b":"str","c":false}`, map[string]interface{}{"a": float64(1), "b": "str", "c": false}},
 
 	"primitive_struct": {