diff --git a/src/ds1307/javaupm_ds1307.i b/src/ds1307/javaupm_ds1307.i
index 4f8d5125..3b0e217f 100644
--- a/src/ds1307/javaupm_ds1307.i
+++ b/src/ds1307/javaupm_ds1307.i
@@ -2,7 +2,7 @@
 %include "../upm.i"
 %include "arrays_java.i";
 
-%apply unsigned char[] {uint8_t *};
+%apply signed char[] {uint8_t *};
 
 %{
     #include "ds1307.h"
diff --git a/src/lcd/javaupm_i2clcd.i b/src/lcd/javaupm_i2clcd.i
index 5cfe3ab7..984aa959 100644
--- a/src/lcd/javaupm_i2clcd.i
+++ b/src/lcd/javaupm_i2clcd.i
@@ -3,8 +3,8 @@
 %include "stdint.i"
 %include "typemaps.i"
 %include "arrays_java.i";
-        
-%apply unsigned char[] {uint8_t *};
+
+%apply signed char[] {uint8_t *};
 %apply uint8_t *OUTPUT { uint8_t *data };
 
 
diff --git a/src/m24lr64e/javaupm_m24lr64e.i b/src/m24lr64e/javaupm_m24lr64e.i
index d74546f8..14d14a9e 100644
--- a/src/m24lr64e/javaupm_m24lr64e.i
+++ b/src/m24lr64e/javaupm_m24lr64e.i
@@ -3,7 +3,7 @@
 %include "stdint.i"
 %include "arrays_java.i";
 
-%apply unsigned char[] {uint8_t *};
+%apply signed char[] {uint8_t *};
 
 %{
     #include "m24lr64e.h"
diff --git a/src/mhz16/javaupm_mhz16.i b/src/mhz16/javaupm_mhz16.i
index dbf0ad99..9a555a71 100644
--- a/src/mhz16/javaupm_mhz16.i
+++ b/src/mhz16/javaupm_mhz16.i
@@ -3,8 +3,8 @@
 %include "cpointer.i"
 %include "typemaps.i"
 %include "arrays_java.i";
-        
-%apply unsigned char[] {unsigned char *};
+
+%apply signed char[] {unsigned char *};
 
 %apply int *OUTPUT { int *gas, int *temp };
 
diff --git a/src/mpr121/javaupm_mpr121.i b/src/mpr121/javaupm_mpr121.i
index 09a03348..f559fa7a 100644
--- a/src/mpr121/javaupm_mpr121.i
+++ b/src/mpr121/javaupm_mpr121.i
@@ -2,7 +2,7 @@
 %include "../upm.i"
 %include "arrays_java.i";
 
-%apply unsigned char[] {uint8_t *};
+%apply signed char[] {uint8_t *};
 
 %{
     #include "mpr121.h"
diff --git a/src/mpu9150/javaupm_mpu9150.i b/src/mpu9150/javaupm_mpu9150.i
index deb45ebf..1e9cb910 100644
--- a/src/mpu9150/javaupm_mpu9150.i
+++ b/src/mpu9150/javaupm_mpu9150.i
@@ -10,7 +10,7 @@
 
 %apply int {mraa::Edge};
 %apply float *INOUT { float *x, float *y, float *z  };
-%apply unsigned char[] {uint8_t *};
+%apply signed char[] {uint8_t *};
 
 %{
     #include "mpu60x0.h"
diff --git a/src/nrf24l01/javaupm_nrf24l01.i b/src/nrf24l01/javaupm_nrf24l01.i
index 93e65957..1d7a3b28 100644
--- a/src/nrf24l01/javaupm_nrf24l01.i
+++ b/src/nrf24l01/javaupm_nrf24l01.i
@@ -2,7 +2,7 @@
 %include "../upm.i"
 
 %include "arrays_java.i";
-%apply unsigned char[] {uint8_t *};
+%apply signed char[] {uint8_t *};
 
 %{
     #include "nrf24l01.h"
diff --git a/src/pn532/javaupm_pn532.i b/src/pn532/javaupm_pn532.i
index 87476612..d9765bd4 100644
--- a/src/pn532/javaupm_pn532.i
+++ b/src/pn532/javaupm_pn532.i
@@ -1,8 +1,12 @@
 %module javaupm_pn532
 %include "../upm.i"
+%include "typemaps.i"
 %include "arrays_java.i"
 
-%apply unsigned char[] {uint8_t *};
+%apply signed char[] {uint8_t *};
+%apply unsigned char *INOUT {uint8_t *responseLength};
+%apply unsigned char *OUTPUT {uint8_t *uidLength};
+
 %ignore i2cContext;
 
 %{