diff --git a/src/native_methods.rs b/src/native_methods.rs
index efd1faf..8255dda 100644
--- a/src/native_methods.rs
+++ b/src/native_methods.rs
@@ -41,6 +41,19 @@ impl EntryPoint {
     }
 }
 
+struct JavaIOFileDescriptor {}
+
+impl JavaIOFileDescriptor {
+
+    fn get_handle(_jvm: &mut JVM) -> Result<JVMCallbackOperation, Error> {
+        Ok(JVMCallbackOperation::ReturnFrame(FieldValue::Long(0)))
+    }
+
+    fn get_append(_jvm: &mut JVM) -> Result<JVMCallbackOperation, Error> {
+        Ok(JVMCallbackOperation::ReturnFrame(FieldValue::Boolean(false))) // TODO: Get append
+    }
+}
+
 struct JavaLangClass {}
 
 impl JavaLangClass {
@@ -895,6 +908,12 @@ impl JdkInternalUtilSystemPropsRaw {
             ("user.name", "java"), // TODO
             ("sun.nio.MaxDirectMemorySize", "9223372036854775807"),
             ("sun.nio.PageAlignDirectMemory", "false"),
+            ("native.encoding", "UTF-8"),
+            ("file.encoding", "UTF-8"),
+            ("sun.jnu.encoding", "UTF-8"),
+            ("os.name", "Unknown"),
+            ("os.version", "Unknown"),
+            ("os.arch", "Unknown"),
         ]; 
         // TODO: Cross-Platform tmpdir
         // TODO: locale detection
@@ -3597,6 +3616,156 @@ pub fn function_for(class_name: &str, m: &crate::classfile::MethodInfo) -> Resul
             },
             todo_call
         ),
+
+        (
+            "java/io/FileInputStream",
+            "open0",
+            MethodDescriptor {
+                argument_types: Box::new([
+                    AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Classname("java/lang/String".to_string())},
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Void() },
+            },
+            todo_call
+        ),
+
+        (
+            "java/io/FileInputStream",
+            "read0",
+            MethodDescriptor {
+                argument_types: Box::new([
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Int() },
+            },
+            todo_call
+        ),
+
+        (
+            "java/io/FileInputStream",
+            "readBytes",
+            MethodDescriptor {
+                argument_types: Box::new([
+                    AbstractTypeDescription { array_level: 1, kind: AbstractTypeKind::Byte() },
+                    AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Int() },
+                    AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Int() },
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Int() },
+            },
+            todo_call
+        ),
+
+        (
+            "java/io/FileInputStream",
+            "length0",
+            MethodDescriptor {
+                argument_types: Box::new([
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Long() },
+            },
+            todo_call
+        ),
+
+        (
+            "java/io/FileInputStream",
+            "position0",
+            MethodDescriptor {
+                argument_types: Box::new([
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Long() },
+            },
+            todo_call
+        ),
+
+        (
+            "java/io/FileInputStream",
+            "skip0",
+            MethodDescriptor {
+                argument_types: Box::new([
+                    AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Long() },
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Long() },
+            },
+            todo_call
+        ),
+
+        (
+            "java/io/FileInputStream",
+            "available0",
+            MethodDescriptor {
+                argument_types: Box::new([
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Int() },
+            },
+            todo_call
+        ),
+
+        (
+            "java/io/FileInputStream",
+            "initIDs",
+            MethodDescriptor {
+                argument_types: Box::new([
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Void() },
+            },
+            ignore_call
+        ),
+
+        (
+            "java/io/FileDescriptor",
+            "sync0",
+            MethodDescriptor {
+                argument_types: Box::new([
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Void() },
+            },
+            todo_call
+        ),
+
+        (
+            "java/io/FileDescriptor",
+            "initIDs",
+            MethodDescriptor {
+                argument_types: Box::new([
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Void() },
+            },
+            ignore_call
+        ),
+
+        (
+            "java/io/FileDescriptor",
+            "getHandle",
+            MethodDescriptor {
+                argument_types: Box::new([
+                    AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Int() },
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Long() },
+            },
+            JavaIOFileDescriptor::get_handle
+        ),
+
+        (
+            "java/io/FileDescriptor",
+            "getAppend",
+            MethodDescriptor {
+                argument_types: Box::new([
+                    AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Int() },
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Boolean() },
+            },
+            JavaIOFileDescriptor::get_append
+        ),
+
+        (
+            "java/io/FileDescriptor",
+            "close0",
+            MethodDescriptor {
+                argument_types: Box::new([
+                ]),
+                return_type: AbstractTypeDescription { array_level: 0, kind: AbstractTypeKind::Void() },
+            },
+            todo_call
+        ),
     ];
 
     for (classname, methodname, methoddescriptor, binding) in native_mappings {