diff --git a/src/ds1307/javaupm_ds1307.i b/src/ds1307/javaupm_ds1307.i
index 3b0e217f..2171974a 100644
--- a/src/ds1307/javaupm_ds1307.i
+++ b/src/ds1307/javaupm_ds1307.i
@@ -2,10 +2,23 @@
 %include "../upm.i"
 %include "arrays_java.i";
 
-%apply signed char[] {uint8_t *};
-
 %{
     #include "ds1307.h"
 %}
 
+%typemap(jni) (uint8_t *buffer, unsigned int len) "jbyteArray";
+%typemap(jtype) (uint8_t *buffer, unsigned int len) "byte[]";
+%typemap(jstype) (uint8_t *buffer, unsigned int len) "byte[]";
+
+%typemap(javain) (uint8_t *buffer, unsigned int len) "$javainput";
+
+%typemap(in) (uint8_t *buffer, unsigned int len) {
+        $1 = (uint8_t *) JCALL2(GetByteArrayElements, jenv, $input, NULL);
+        $2 = JCALL1(GetArrayLength, jenv, $input);
+}
+
+%typemap(freearg) (uint8_t *buffer, unsigned int len) {
+        JCALL3(ReleaseByteArrayElements, jenv, $input, (jbyte *)$1, 0);
+}
+
 %include "ds1307.h"