diff --git a/include/common/standard.h b/include/common/standard.h
index 7de8ead28..9447e3669 100644
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -1081,7 +1081,7 @@ char *env_expand(char *in);
 /* displays a <len> long memory block at <buf>, assuming first byte of <buf>
  * has address <baseaddr>. The output is emitted to file <out>.
  */
-void debug_hexdump(FILE *out, char *buf, unsigned int baseaddr, int len);
+void debug_hexdump(FILE *out, const char *buf, unsigned int baseaddr, int len);
 
 /* used from everywhere just to drain results we don't want to read and which
  * recent versions of gcc increasingly and annoyingly complain about.
diff --git a/src/standard.c b/src/standard.c
index 95d83e49c..1d7625486 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -3782,7 +3782,7 @@ int dump_text_line(struct chunk *out, const char *buf, int bsize, int len,
 /* displays a <len> long memory block at <buf>, assuming first byte of <buf>
  * has address <baseaddr>. The output is emitted to file <out>.
  */
-void debug_hexdump(FILE *out, char *buf, unsigned int baseaddr, int len)
+void debug_hexdump(FILE *out, const char *buf, unsigned int baseaddr, int len)
 {
 	unsigned int i;
 	int b, j;