diff --git a/builtin/log.c b/builtin/log.c
index 91466c059c79..a06e5385689b 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1231,14 +1231,20 @@ static void make_cover_letter(struct rev_info *rev, int use_separate_file,
 		 */
 		struct diff_options opts;
 		struct strvec other_arg = STRVEC_INIT;
+		struct range_diff_options range_diff_opts = {
+			.creation_factor = rev->creation_factor,
+			.dual_color = 1,
+			.diffopt = &opts,
+			.other_arg = &other_arg
+		};
+
 		diff_setup(&opts);
 		opts.file = rev->diffopt.file;
 		opts.use_color = rev->diffopt.use_color;
 		diff_setup_done(&opts);
 		fprintf_ln(rev->diffopt.file, "%s", rev->rdiff_title);
 		get_notes_args(&other_arg, rev);
-		show_range_diff(rev->rdiff1, rev->rdiff2,
-				rev->creation_factor, 1, &opts, &other_arg);
+		show_range_diff(rev->rdiff1, rev->rdiff2, &range_diff_opts);
 		strvec_clear(&other_arg);
 	}
 }
diff --git a/builtin/range-diff.c b/builtin/range-diff.c
index 5b1f6326322f..80fcdc6ad42d 100644
--- a/builtin/range-diff.c
+++ b/builtin/range-diff.c
@@ -14,12 +14,17 @@ NULL
 
 int cmd_range_diff(int argc, const char **argv, const char *prefix)
 {
-	int creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT;
 	struct diff_options diffopt = { NULL };
 	struct strvec other_arg = STRVEC_INIT;
+	struct range_diff_options range_diff_opts = {
+		.creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT,
+		.diffopt = &diffopt,
+		.other_arg = &other_arg
+	};
 	int simple_color = -1;
 	struct option range_diff_options[] = {
-		OPT_INTEGER(0, "creation-factor", &creation_factor,
+		OPT_INTEGER(0, "creation-factor",
+			    &range_diff_opts.creation_factor,
 			    N_("Percentage by which creation is weighted")),
 		OPT_BOOL(0, "no-dual-color", &simple_color,
 			    N_("use simple diff colors")),
@@ -82,8 +87,8 @@ int cmd_range_diff(int argc, const char **argv, const char *prefix)
 	}
 	FREE_AND_NULL(options);
 
-	res = show_range_diff(range1.buf, range2.buf, creation_factor,
-			      simple_color < 1, &diffopt, &other_arg);
+	range_diff_opts.dual_color = simple_color < 1;
+	res = show_range_diff(range1.buf, range2.buf, &range_diff_opts);
 
 	strvec_clear(&other_arg);
 	strbuf_release(&range1);
diff --git a/log-tree.c b/log-tree.c
index fd0dde97ec32..eeacba15dc94 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -808,6 +808,11 @@ void show_log(struct rev_info *opt)
 	if (cmit_fmt_is_mail(ctx.fmt) && opt->rdiff1) {
 		struct diff_queue_struct dq;
 		struct diff_options opts;
+		struct range_diff_options range_diff_opts = {
+			.creation_factor = opt->creation_factor,
+			.dual_color = 1,
+			.diffopt = &opts
+		};
 
 		memcpy(&dq, &diff_queued_diff, sizeof(diff_queued_diff));
 		DIFF_QUEUE_CLEAR(&diff_queued_diff);
@@ -822,8 +827,7 @@ void show_log(struct rev_info *opt)
 		opts.file = opt->diffopt.file;
 		opts.use_color = opt->diffopt.use_color;
 		diff_setup_done(&opts);
-		show_range_diff(opt->rdiff1, opt->rdiff2,
-				opt->creation_factor, 1, &opts, NULL);
+		show_range_diff(opt->rdiff1, opt->rdiff2, &range_diff_opts);
 
 		memcpy(&diff_queued_diff, &dq, sizeof(diff_queued_diff));
 	}
diff --git a/range-diff.c b/range-diff.c
index d0d941a25add..25d4c244799c 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -526,33 +526,32 @@ static struct strbuf *output_prefix_cb(struct diff_options *opt, void *data)
 }
 
 int show_range_diff(const char *range1, const char *range2,
-		    int creation_factor, int dual_color,
-		    const struct diff_options *diffopt,
-		    const struct strvec *other_arg)
+		    struct range_diff_options *range_diff_opts)
 {
 	int res = 0;
 
 	struct string_list branch1 = STRING_LIST_INIT_DUP;
 	struct string_list branch2 = STRING_LIST_INIT_DUP;
 
-	if (read_patches(range1, &branch1, other_arg))
+	if (read_patches(range1, &branch1, range_diff_opts->other_arg))
 		res = error(_("could not parse log for '%s'"), range1);
-	if (!res && read_patches(range2, &branch2, other_arg))
+	if (!res && read_patches(range2, &branch2, range_diff_opts->other_arg))
 		res = error(_("could not parse log for '%s'"), range2);
 
 	if (!res) {
 		struct diff_options opts;
 		struct strbuf indent = STRBUF_INIT;
 
-		if (diffopt)
-			memcpy(&opts, diffopt, sizeof(opts));
+		if (range_diff_opts->diffopt)
+			memcpy(&opts, range_diff_opts->diffopt, sizeof(opts));
 		else
 			diff_setup(&opts);
 
 		if (!opts.output_format)
 			opts.output_format = DIFF_FORMAT_PATCH;
 		opts.flags.suppress_diff_headers = 1;
-		opts.flags.dual_color_diffed_diffs = dual_color;
+		opts.flags.dual_color_diffed_diffs =
+			range_diff_opts->dual_color;
 		opts.flags.suppress_hunk_header_line_count = 1;
 		opts.output_prefix = output_prefix_cb;
 		strbuf_addstr(&indent, "    ");
@@ -560,7 +559,8 @@ int show_range_diff(const char *range1, const char *range2,
 		diff_setup_done(&opts);
 
 		find_exact_matches(&branch1, &branch2);
-		get_correspondences(&branch1, &branch2, creation_factor);
+		get_correspondences(&branch1, &branch2,
+				    range_diff_opts->creation_factor);
 		output(&branch1, &branch2, &opts);
 
 		strbuf_release(&indent);
diff --git a/range-diff.h b/range-diff.h
index 4abd70c40fed..a595f4e8db2d 100644
--- a/range-diff.h
+++ b/range-diff.h
@@ -6,15 +6,19 @@
 
 #define RANGE_DIFF_CREATION_FACTOR_DEFAULT 60
 
+struct range_diff_options {
+	int creation_factor;
+	unsigned dual_color:1;
+	const struct diff_options *diffopt; /* may be NULL */
+	const struct strvec *other_arg; /* may be NULL */
+};
+
 /*
- * Compare series of commits in RANGE1 and RANGE2, and emit to the
- * standard output.  NULL can be passed to DIFFOPT to use the built-in
- * default.
+ * Compare series of commits in `range1` and `range2`, and emit to the
+ * standard output.
  */
 int show_range_diff(const char *range1, const char *range2,
-		    int creation_factor, int dual_color,
-		    const struct diff_options *diffopt,
-		    const struct strvec *other_arg);
+		    struct range_diff_options *opts);
 
 /*
  * Determine whether the given argument is usable as a range argument of `git
