diff --git a/utils.cc b/utils.cc
index ee4bd1f29..8a0febdb2 100644
--- a/utils.cc
+++ b/utils.cc
@@ -185,7 +185,7 @@ int wildtest(char *wild, char *test) {
 }
 
 /* Wrapper for nbase function hexdump. */
-void nmap_hexdump(unsigned char *cp, unsigned int length) {
+void nmap_hexdump(const unsigned char *cp, unsigned int length) {
   char *string = NULL;
 
   string = hexdump((u8*) cp, length);
diff --git a/utils.h b/utils.h
index 7c88c3e33..9b6485149 100644
--- a/utils.h
+++ b/utils.h
@@ -170,7 +170,7 @@ template<class T> T box(T bmin, T bmax, T bnum) {
 
 int wildtest(char *wild, char *test);
 
-void nmap_hexdump(unsigned char *cp, unsigned int length);
+void nmap_hexdump(const unsigned char *cp, unsigned int length);
 
 void genfry(unsigned char *arr, int elem_sz, int num_elem);
 void shortfry(unsigned short *arr, int num_elem);