diff --git a/config.c b/config.c
index d997c55e33..00a11b5d98 100644
--- a/config.c
+++ b/config.c
@@ -1551,12 +1551,8 @@ static int git_default_core_config(const char *var, const char *value,
 		return 0;
 	}
 
-	if (!strcmp(var, "core.checkroundtripencoding")) {
-		if (!value)
-			return config_error_nonbool(var);
-		check_roundtrip_encoding = xstrdup(value);
-		return 0;
-	}
+	if (!strcmp(var, "core.checkroundtripencoding"))
+		return git_config_string(&check_roundtrip_encoding, var, value);
 
 	if (!strcmp(var, "core.notesref")) {
 		if (!value)
diff --git a/convert.h b/convert.h
index d925589444..ab8b4fa68d 100644
--- a/convert.h
+++ b/convert.h
@@ -92,7 +92,7 @@ void convert_attrs(struct index_state *istate,
 		   struct conv_attrs *ca, const char *path);
 
 extern enum eol core_eol;
-extern char *check_roundtrip_encoding;
+extern const char *check_roundtrip_encoding;
 const char *get_cached_convert_stats_ascii(struct index_state *istate,
 					   const char *path);
 const char *get_wt_convert_stats_ascii(const char *path);
diff --git a/environment.c b/environment.c
index 9e37bf58c0..90632a39bc 100644
--- a/environment.c
+++ b/environment.c
@@ -64,7 +64,7 @@ const char *excludes_file;
 enum auto_crlf auto_crlf = AUTO_CRLF_FALSE;
 enum eol core_eol = EOL_UNSET;
 int global_conv_flags_eol = CONV_EOL_RNDTRP_WARN;
-char *check_roundtrip_encoding = "SHIFT-JIS";
+const char *check_roundtrip_encoding = "SHIFT-JIS";
 enum branch_track git_branch_track = BRANCH_TRACK_REMOTE;
 enum rebase_setup_type autorebase = AUTOREBASE_NEVER;
 enum push_default_type push_default = PUSH_DEFAULT_UNSPECIFIED;