diff --git a/epan/charsets.c b/epan/charsets.c
index 59da769aa1..c6359b0df3 100644
--- a/epan/charsets.c
+++ b/epan/charsets.c
@@ -21,8 +21,12 @@
 
 #include "charsets.h"
 
-/* REPLACEMENT CHARACTER */
-#define UNREPL 0xFFFD
+/*
+ * 6-character abbreviation for "Unicode REPLACEMENT CHARACTER", so it
+ * takes up the same amount of space as the 6-character hex values for
+ * Basic Multilingual Plane code points in the tables below.
+ */
+#define UNREPL UNICODE_REPLACEMENT_CHARACTER
 
 /*
  * Wikipedia's "Character encoding" template, giving a pile of character
diff --git a/include/ws_codepoints.h b/include/ws_codepoints.h
new file mode 100644
index 0000000000..338cef5a49
--- /dev/null
+++ b/include/ws_codepoints.h
@@ -0,0 +1,24 @@
+/* ws_codepoints.h
+ * Unicode code point definitions
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 2006 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef __WS_CODEPOINTS_H__
+#define __WS_CODEPOINTS_H__
+
+/**
+ * @file
+ * Unicode code points.
+ *
+ * (See chapter 2 of the Unicode standard for an explanation of what
+ * "characters" and "code points" are.)
+ */
+
+#define UNICODE_REPLACEMENT_CHARACTER 0x00FFFD
+
+#endif /* __WS_CODEPOINTS_H__ */
diff --git a/wsutil/str_util.c b/wsutil/str_util.c
index 0d6e1694b8..bc6c04b024 100644
--- a/wsutil/str_util.c
+++ b/wsutil/str_util.c
@@ -14,6 +14,8 @@
 
 #include <string.h>
 
+#include <ws_codepoints.h>
+
 #include <wsutil/to_str.h>
 
 
@@ -626,11 +628,6 @@ ws_strdup_underline(wmem_allocator_t *allocator, long offset, size_t len)
 #define FMTBUF_ENDSTR \
     fmtbuf[column] = '\0'
 
-/* REPLACEMENT CHARACTER */
-#define UNREPL 0xFFFD
-
-#define UNPOOP 0x1F4A9
-
 static gchar *
 format_text_internal(wmem_allocator_t *allocator,
                         const guchar *string, size_t len,
@@ -761,7 +758,7 @@ format_text_internal(wmem_allocator_t *allocator,
                          * instead, and then continue the loop, which
                          * will terminate.
                          */
-                        uc = UNREPL;
+                        uc = UNICODE_REPLACEMENT_CHARACTER;
                         break;
                     }
                     c = *string;
@@ -771,7 +768,7 @@ format_text_internal(wmem_allocator_t *allocator,
                          * a replacement character, and then re-process
                          * this octet as the beginning of a new character.
                          */
-                        uc = UNREPL;
+                        uc = UNICODE_REPLACEMENT_CHARACTER;
                         break;
                     }
                     string++;
@@ -783,10 +780,10 @@ format_text_internal(wmem_allocator_t *allocator,
                  * a REPLACEMENT CHARACTER.
                  */
                 if (!g_unichar_validate(uc))
-                    uc = UNREPL;
+                    uc = UNICODE_REPLACEMENT_CHARACTER;
             } else {
                 /* 0xfe or 0xff; put it a REPLACEMENT CHARACTER */
-                uc = UNREPL;
+                uc = UNICODE_REPLACEMENT_CHARACTER;
             }
 
             /*
diff --git a/wsutil/wmem/wmem_strbuf.h b/wsutil/wmem/wmem_strbuf.h
index 680fe85c97..7bcce47bf2 100644
--- a/wsutil/wmem/wmem_strbuf.h
+++ b/wsutil/wmem/wmem_strbuf.h
@@ -12,6 +12,8 @@
 #ifndef __WMEM_STRBUF_H__
 #define __WMEM_STRBUF_H__
 
+#include <ws_codepoints.h>
+
 #include "wmem_core.h"
 
 #ifdef __cplusplus
@@ -103,7 +105,7 @@ void
 wmem_strbuf_append_unichar(wmem_strbuf_t *strbuf, const gunichar c);
 
 #define wmem_strbuf_append_unichar_repl(buf) \
-            wmem_strbuf_append_unichar(buf, 0xfffd)
+            wmem_strbuf_append_unichar(buf, UNICODE_REPLACEMENT_CHARACTER)
 
 WS_DLL_PUBLIC
 void
diff --git a/wsutil/ws_getopt.c b/wsutil/ws_getopt.c
index 68a72661f9..37354dddd7 100644
--- a/wsutil/ws_getopt.c
+++ b/wsutil/ws_getopt.c
@@ -32,6 +32,8 @@
 #include <string.h>
 #include <wchar.h>
 
+#include <ws_codepoints.h>
+
 #include <wsutil/ws_getopt.h>
 
 char *ws_optarg;
@@ -94,7 +96,7 @@ int ws_getopt(int argc, char * const argv[], const char *optstring)
 	if (!ws_optpos) ws_optpos++;
 	if ((k = mbtowc(&c, argv[ws_optind]+ws_optpos, MB_LEN_MAX)) < 0) {
 		k = 1;
-		c = 0xfffd; /* replacement char */
+		c = UNICODE_REPLACEMENT_CHARACTER; /* replacement char */
 	}
 	optchar = argv[ws_optind]+ws_optpos;
 	ws_optpos += k;