diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i
index feb8c9c..3e09d3a 100644
--- a/pylibfdt/libfdt.i
+++ b/pylibfdt/libfdt.i
@@ -18,7 +18,7 @@
  * a struct called fdt_property. That struct causes swig to create a class in
  * libfdt.py called fdt_property(), which confuses things.
  */
-static int fdt_property_stub(void *fdt, const char *name, const char *val,
+static int fdt_property_stub(void *fdt, const char *name, const void *val,
                              int len)
 {
     return fdt_property(fdt, name, val, len);
@@ -930,7 +930,7 @@ class FdtSw(FdtRo):
 
         Args:
             name: Name of property to add
-            val: Value of property
+            val: Value of property (bytes)
             quiet: Errors to ignore (empty to raise on all errors)
 
         Raises:
@@ -1113,6 +1113,6 @@ int fdt_property_cell(void *fdt, const char *name, uint32_t val);
  * This function has a stub since the name fdt_property is used for both a
   * function and a struct, which confuses SWIG.
  */
-int fdt_property_stub(void *fdt, const char *name, const char *val, int len);
+int fdt_property_stub(void *fdt, const char *name, const void *val, int len);
 
 %include <libfdt.h>
diff --git a/tests/pylibfdt_tests.py b/tests/pylibfdt_tests.py
index 509cf14..021a5a8 100644
--- a/tests/pylibfdt_tests.py
+++ b/tests/pylibfdt_tests.py
@@ -522,8 +522,9 @@ class PyLibfdtSwTests(unittest.TestCase):
         sw.property_string('compatible', 'subnode1')
         sw.property_u32('reg', 1)
         sw.property_cell('prop-int', TEST_VALUE_1)
+        sw.property('data', b'\x00data\x01')
         sw.begin_node('subsubnode')
-        sw.property('compatible', 'subsubnode1\0subsubnode')
+        sw.property('compatible', b'subsubnode1\0subsubnode')
         sw.property_cell('prop-int', TEST_VALUE_1)
         sw.end_node()
         sw.begin_node('ss1')
@@ -540,7 +541,7 @@ class PyLibfdtSwTests(unittest.TestCase):
                 with sw.add_node('subsubnode@0'):
                     sw.property_u32('reg', 0)
                     sw.property_cell('phandle', PHANDLE_2)
-                    sw.property('compatible', 'subsubnode2\0subsubnode')
+                    sw.property('compatible', b'subsubnode2\0subsubnode')
                     sw.property_cell('prop-int', TEST_VALUE_2)
                 with sw.add_node('ss2'):
                     pass