diff --git a/Cargo.toml b/Cargo.toml
index 11aa483..3d01084 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,9 +25,9 @@ itertools = "0.14"
 pbjson = { path = "pbjson", version = "0.8" }
 pbjson-build = { path = "pbjson-build", version = "0.8" }
 pbjson-types = { path = "pbjson-types", version = "0.8" }
-prost = "0.14"
-prost-build = "0.14"
-prost-types = "0.14"
+prost = { git = "https://github.com/blizzardfinnegan/prost.git", rev = "d20b25c7ad45182da894ed7a559f869360c4bc36" }
+prost-build = { git = "https://github.com/blizzardfinnegan/prost.git", rev = "d20b25c7ad45182da894ed7a559f869360c4bc36" }
+prost-types = { git = "https://github.com/blizzardfinnegan/prost.git", rev = "d20b25c7ad45182da894ed7a559f869360c4bc36" }
 rand = "0.9"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
diff --git a/pbjson-build/src/generator/message.rs b/pbjson-build/src/generator/message.rs
index 0ecaa8d..36dbdc2 100644
--- a/pbjson-build/src/generator/message.rs
+++ b/pbjson-build/src/generator/message.rs
@@ -42,6 +42,7 @@ pub fn generate_message<W: Write>(
     btree_map_paths: &[String],
     emit_fields: bool,
     preserve_proto_field_names: bool,
+    unknown_field_storage_field: &Option<String>,
 ) -> Result<()> {
     let rust_type = resolver.rust_type(&message.path);
 
@@ -67,6 +68,7 @@ pub fn generate_message<W: Write>(
         writer,
         ignore_unknown_fields,
         btree_map_paths,
+        unknown_field_storage_field,
     )?;
     write_deserialize_end(0, writer)?;
     Ok(())
@@ -514,6 +516,7 @@ fn write_deserialize_message<W: Write>(
     writer: &mut W,
     ignore_unknown_fields: bool,
     btree_map_paths: &[String],
+    unknown_field_storage_field: &Option<String>,
 ) -> Result<()> {
     write_deserialize_field_name(2, message, writer, ignore_unknown_fields)?;
 
@@ -655,6 +658,15 @@ fn write_deserialize_message<W: Write>(
         )?;
     }
 
+    if let Some(unknown_field_storage_field) = unknown_field_storage_field {
+        writeln!(
+            writer,
+            "{indent}{unknown_field_field}: Default::default(),",
+            indent = Indent(indent + 3),
+            unknown_field_field = unknown_field_storage_field
+        )?;
+    }
+
     writeln!(writer, "{}}})", Indent(indent + 2))?;
     writeln!(writer, "{}}}", Indent(indent + 1))?;
     writeln!(writer, "{}}}", Indent(indent))?;
diff --git a/pbjson-build/src/lib.rs b/pbjson-build/src/lib.rs
index 839506c..0374dc7 100644
--- a/pbjson-build/src/lib.rs
+++ b/pbjson-build/src/lib.rs
@@ -109,6 +109,7 @@ pub struct Builder {
     use_integers_for_enums: bool,
     ignore_unknown_enum_variants: bool,
     preserve_proto_field_names: bool,
+    unknown_fields_storage_field: Option<String>,
 }
 
 impl Builder {
@@ -207,6 +208,13 @@ impl Builder {
         self
     }
 
+    /// Store unknown fields in the specified field when constructing.
+    /// This field is used when using prost generated code with unknown_field support
+    pub fn unknown_fields_storage_field<S: Into<String>>(&mut self, field_name: S) -> &mut Self {
+        self.unknown_fields_storage_field = Some(field_name.into());
+        self
+    }
+
     /// Generates code for all registered types where `prefixes` contains a prefix of
     /// the fully-qualified path of the type
     pub fn build<S: AsRef<str>>(&mut self, prefixes: &[S]) -> Result<()> {
@@ -295,6 +303,7 @@ impl Builder {
                             &self.btree_map_paths,
                             self.emit_fields,
                             self.preserve_proto_field_names,
+                            &self.unknown_fields_storage_field,
                         )?
                     }
                 }
diff --git a/pbjson-test/build.rs b/pbjson-test/build.rs
index d9283bd..13fa26e 100644
--- a/pbjson-test/build.rs
+++ b/pbjson-test/build.rs
@@ -30,7 +30,8 @@ fn main() -> Result<()> {
         .extern_path(".google.protobuf", "::pbjson_types")
         .extern_path(".test.external", "crate")
         .bytes([".test"])
-        .protoc_arg("--experimental_allow_proto3_optional");
+        .protoc_arg("--experimental_allow_proto3_optional")
+        .include_unknown_fields(".", "_unknown_fields");
 
     if cfg!(feature = "btree") {
         prost_config.btree_map([".test"]);
@@ -68,6 +69,8 @@ fn main() -> Result<()> {
         builder.preserve_proto_field_names();
     }
 
+    builder.unknown_fields_storage_field("_unknown_fields");
+
     builder.build(&[".test"])?;
 
     Ok(())
diff --git a/pbjson-test/src/lib.rs b/pbjson-test/src/lib.rs
index 45dde55..799dab4 100644
--- a/pbjson-test/src/lib.rs
+++ b/pbjson-test/src/lib.rs
@@ -158,7 +158,9 @@ mod tests {
     #[test]
     #[cfg(not(feature = "ignore-unknown-fields"))]
     fn test_unknown_field_error() {
-        let message = Empty {};
+        let message = Empty {
+            ..Default::default()
+        };
 
         let encoded = serde_json::to_string(&message).unwrap();
         let _decoded: Empty = serde_json::from_str(&encoded).unwrap();
@@ -179,13 +181,20 @@ mod tests {
     #[test]
     #[cfg(feature = "ignore-unknown-fields")]
     fn test_ignore_unknown_field() {
-        let message = Empty {};
+        let message = Empty {
+            ..Default::default()
+        };
 
         let encoded = serde_json::to_string(&message).unwrap();
         let _decoded: Empty = serde_json::from_str(&encoded).unwrap();
 
         let empty = serde_json::from_str::<Empty>("{\n \"foo\": \"bar\"\n}").unwrap();
-        assert_eq!(empty, Empty {});
+        assert_eq!(
+            empty,
+            Empty {
+                ..Default::default()
+            }
+        );
     }
 
     #[test]
@@ -787,12 +796,17 @@ mod tests {
     fn test_escaped() -> Result<(), Box<dyn Error>> {
         use super::test::escape::{Abstract, Target, Type};
 
-        let r#type = Type { example: true };
+        let r#type = Type {
+            example: true,
+            ..Default::default()
+        };
         let r#abstract = Abstract {
             r#type: Some(r#type),
+            ..Default::default()
         };
         let target = Target {
             r#abstract: Some(r#abstract),
+            ..Default::default()
         };
 
         let encoded = serde_json::to_string(&target)?;