diff --git a/src/main/java/me/itzg/helpers/patch/Json5FileFormat.java b/src/main/java/me/itzg/helpers/patch/Json5FileFormat.java
new file mode 100644
index 00000000..81bbbe12
--- /dev/null
+++ b/src/main/java/me/itzg/helpers/patch/Json5FileFormat.java
@@ -0,0 +1,64 @@
+package me.itzg.helpers.patch;
+
+import com.fasterxml.jackson.core.json.JsonReadFeature;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectWriter;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+
+import java.io.IOException;
+import java.util.Map;
+
+public class Json5FileFormat implements FileFormat {
+
+    private static final String[] SUFFIXES = {"json5"};
+    private static final TypeReference<Map<String, Object>> MAP_TYPE
+            = new TypeReference<Map<String, Object>>() {
+    };
+
+    private final ObjectMapper objectMapper;
+    private final ObjectWriter objectWriter;
+
+    // Currently, missing additional whitespace character support and hexadecimal numbers
+    // Check https://github.com/FasterXML/jackson-core/wiki/JsonReadFeatures to see if/when they become available
+    public Json5FileFormat() {
+        objectMapper = JsonMapper.builder().enable(
+                JsonReadFeature.ALLOW_TRAILING_COMMA,
+                JsonReadFeature.ALLOW_NON_NUMERIC_NUMBERS,
+                JsonReadFeature.ALLOW_LEADING_PLUS_SIGN_FOR_NUMBERS,
+                JsonReadFeature.ALLOW_LEADING_DECIMAL_POINT_FOR_NUMBERS,
+                JsonReadFeature.ALLOW_JAVA_COMMENTS,
+                JsonReadFeature.ALLOW_BACKSLASH_ESCAPING_ANY_CHARACTER,
+                JsonReadFeature.ALLOW_TRAILING_DECIMAL_POINT_FOR_NUMBERS,
+                JsonReadFeature.ALLOW_UNQUOTED_FIELD_NAMES,
+                JsonReadFeature.ALLOW_SINGLE_QUOTES,
+                JsonReadFeature.ALLOW_UNESCAPED_CONTROL_CHARS
+        ).build();
+
+        objectWriter = objectMapper.writer(
+                new DefaultPrettyPrinter()
+                        .withoutSpacesInObjectEntries()
+        );
+    }
+
+    @Override
+    public String[] getFileSuffixes() {
+        return SUFFIXES;
+    }
+
+    @Override
+    public String getName() {
+        return "json5";
+    }
+
+    @Override
+    public Map<String, Object> decode(String content) throws IOException {
+        return objectMapper.readValue(content, MAP_TYPE);
+    }
+
+    @Override
+    public String encode(Map<String, Object> content) throws IOException {
+        return objectWriter.writeValueAsString(content);
+    }
+}
diff --git a/src/main/java/me/itzg/helpers/patch/PatchSetProcessor.java b/src/main/java/me/itzg/helpers/patch/PatchSetProcessor.java
index 7749078f..61db134b 100644
--- a/src/main/java/me/itzg/helpers/patch/PatchSetProcessor.java
+++ b/src/main/java/me/itzg/helpers/patch/PatchSetProcessor.java
@@ -29,6 +29,7 @@ public PatchSetProcessor(Interpolator interpolator) {
 
     private final FileFormat[] fileFormats = new FileFormat[]{
             new JsonFileFormat(),
+            new Json5FileFormat(),
             new YamlFileFormat()
     };
 
diff --git a/src/test/java/me/itzg/helpers/patch/PatchSetProcessorTest.java b/src/test/java/me/itzg/helpers/patch/PatchSetProcessorTest.java
index 4381888b..eb1ee614 100644
--- a/src/test/java/me/itzg/helpers/patch/PatchSetProcessorTest.java
+++ b/src/test/java/me/itzg/helpers/patch/PatchSetProcessorTest.java
@@ -54,6 +54,32 @@ void setInJson(@TempDir Path tempDir) throws IOException {
         );
     }
 
+    @Test
+    void setInJson5(@TempDir Path tempDir) throws IOException {
+        final Path src = tempDir.resolve("testing.json5");
+        Files.copy(Paths.get("src/test/resources/patch/testing.json5"), src);
+
+        final PatchSetProcessor processor = new PatchSetProcessor(
+                new Interpolator(environmentVariablesProvider, "CFG_")
+        );
+
+        processor.process(new PatchSet()
+                .setPatches(Arrays.asList(
+                        new PatchDefinition()
+                                .setFile(src)
+                                .setOps(Arrays.asList(
+                                        new PatchSetOperation()
+                                                .setPath("$.outer.field1")
+                                                .setValue(new TextNode("new value"))
+                                ))
+                ))
+        );
+
+        assertThat(src).hasSameTextualContentAs(
+                Paths.get("src/test/resources/patch/expected-setInJson5.json5")
+        );
+    }
+
     @Test
     void setInYaml(@TempDir Path tempDir) throws IOException {
         final Path src = tempDir.resolve("testing.yaml");
diff --git a/src/test/resources/patch/expected-setInJson5.json5 b/src/test/resources/patch/expected-setInJson5.json5
new file mode 100644
index 00000000..56003edd
--- /dev/null
+++ b/src/test/resources/patch/expected-setInJson5.json5
@@ -0,0 +1,14 @@
+{
+  "outer":{
+    "field1":"new value"
+  },
+  "unquoted":"and you can quote me on that",
+  "singleQuotes":"I can use \"double quotes\" here",
+  "lineBreaks":"Look, Mom! \nNo \\n's!",
+  "leadingDecimalPoint":0.8675309,
+  "andTrailing":8675309.0,
+  "positiveSign":1,
+  "trailingComma":"in objects",
+  "andIn":[ "arrays" ],
+  "backwardsCompatible":"with JSON"
+}
\ No newline at end of file
diff --git a/src/test/resources/patch/testing.json5 b/src/test/resources/patch/testing.json5
new file mode 100644
index 00000000..1c09f56d
--- /dev/null
+++ b/src/test/resources/patch/testing.json5
@@ -0,0 +1,14 @@
+{
+  // comments
+  outer: {
+    field1: "old"
+  },
+  unquoted: 'and you can quote me on that',
+  singleQuotes: 'I can use "double quotes" here',
+  lineBreaks: "Look, Mom! \
+No \\n's!",
+  leadingDecimalPoint: .8675309, andTrailing: 8675309.,
+  positiveSign: +1,
+  trailingComma: 'in objects', andIn: ['arrays',],
+  "backwardsCompatible": "with JSON",
+}
\ No newline at end of file