diff --git a/device_tree.c b/device_tree.c
index acae53e..b366fdd 100644
--- a/device_tree.c
+++ b/device_tree.c
@@ -127,7 +127,7 @@
 }
 
 int qemu_devtree_setprop(void *fdt, const char *node_path,
-                         const char *property, void *val_array, int size)
+                         const char *property, const void *val_array, int size)
 {
     int r;
 
diff --git a/device_tree.h b/device_tree.h
index 4898d95..2244270 100644
--- a/device_tree.h
+++ b/device_tree.h
@@ -18,7 +18,7 @@
 void *load_device_tree(const char *filename_path, int *sizep);
 
 int qemu_devtree_setprop(void *fdt, const char *node_path,
-                         const char *property, void *val_array, int size);
+                         const char *property, const void *val_array, int size);
 int qemu_devtree_setprop_cell(void *fdt, const char *node_path,
                               const char *property, uint32_t val);
 int qemu_devtree_setprop_u64(void *fdt, const char *node_path,