diff --git a/builtin/diff.c b/builtin/diff.c
index c0f564273a..55e7d21755 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -474,9 +474,7 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 	repo_init_revisions(the_repository, &rev, prefix);
 
 	/* Set up defaults that will apply to both no-index and regular diffs. */
-	rev.diffopt.stat_width = -1;
-	rev.diffopt.stat_name_width = -1;
-	rev.diffopt.stat_graph_width = -1;
+	init_diffstat_widths(&rev.diffopt);
 	rev.diffopt.flags.allow_external = 1;
 	rev.diffopt.flags.allow_textconv = 1;
 
diff --git a/builtin/log.c b/builtin/log.c
index 80e1be1645..ba775d7b5c 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -176,17 +176,15 @@ static void cmd_log_init_defaults(struct rev_info *rev)
 	if (default_follow)
 		rev->diffopt.flags.default_follow_renames = 1;
 	rev->verbose_header = 1;
+	init_diffstat_widths(&rev->diffopt);
 	rev->diffopt.flags.recursive = 1;
-	rev->diffopt.stat_width = -1; /* use full terminal width */
-	rev->diffopt.stat_name_width = -1; /* respect statNameWidth config */
-	rev->diffopt.stat_graph_width = -1; /* respect statGraphWidth config */
+	rev->diffopt.flags.allow_textconv = 1;
 	rev->abbrev_commit = default_abbrev_commit;
 	rev->show_root_diff = default_show_root;
 	rev->subject_prefix = fmt_patch_subject_prefix;
 	rev->patch_name_max = fmt_patch_name_max;
 	rev->show_signature = default_show_signature;
 	rev->encode_email_headers = default_encode_email_headers;
-	rev->diffopt.flags.allow_textconv = 1;
 
 	if (default_date_mode)
 		parse_date_format(default_date_mode, &rev->date_mode);
diff --git a/builtin/merge.c b/builtin/merge.c
index fd21c0d4f4..8f397cbeff 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -466,9 +466,7 @@ static void finish(struct commit *head_commit,
 	if (new_head && show_diffstat) {
 		struct diff_options opts;
 		repo_diff_setup(the_repository, &opts);
-		opts.stat_width = -1; /* use full terminal width */
-		opts.stat_name_width = -1; /* respect statNameWidth config */
-		opts.stat_graph_width = -1; /* respect statGraphWidth config */
+		init_diffstat_widths(&opts);
 		opts.output_format |=
 			DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 		opts.detect_rename = DIFF_DETECT_RENAME;
diff --git a/builtin/rebase.c b/builtin/rebase.c
index b93dca95a6..4783f90ac5 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1806,9 +1806,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 
 		/* We want color (if set), but no pager */
 		repo_diff_setup(the_repository, &opts);
-		opts.stat_width = -1; /* use full terminal width */
-		opts.stat_name_width = -1; /* respect statNameWidth config */
-		opts.stat_graph_width = -1; /* respect statGraphWidth config */
+		init_diffstat_widths(&opts);
 		opts.output_format |=
 			DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 		opts.detect_rename = DIFF_DETECT_RENAME;
diff --git a/diff.c b/diff.c
index 353e3b2cc9..2c602df10a 100644
--- a/diff.c
+++ b/diff.c
@@ -6936,6 +6936,13 @@ void diff_queued_diff_prefetch(void *repository)
 	oid_array_clear(&to_fetch);
 }
 
+void init_diffstat_widths(struct diff_options *options)
+{
+	options->stat_width = -1;        /* use full terminal width */
+	options->stat_name_width = -1;   /* respect diff.statNameWidth config */
+	options->stat_graph_width = -1;  /* respect diff.statGraphWidth config */
+}
+
 void diffcore_std(struct diff_options *options)
 {
 	int output_formats_to_prefetch = DIFF_FORMAT_DIFFSTAT |
diff --git a/diff.h b/diff.h
index caf1528bf0..66bd8aeb29 100644
--- a/diff.h
+++ b/diff.h
@@ -573,6 +573,7 @@ int git_config_rename(const char *var, const char *value);
 
 #define DIFF_PICKAXE_IGNORE_CASE	32
 
+void init_diffstat_widths(struct diff_options *);
 void diffcore_std(struct diff_options *);
 void diffcore_fix_diff_index(void);
 
diff --git a/t/t4052-stat-output.sh b/t/t4052-stat-output.sh
index beb2ec2a55..7badd72488 100755
--- a/t/t4052-stat-output.sh
+++ b/t/t4052-stat-output.sh
@@ -12,7 +12,7 @@ TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-terminal.sh
 
-# 120 character name
+# 120-character name
 name=aaaaaaaaaa
 name=$name$name$name$name$name$name$name$name$name$name$name$name
 test_expect_success 'preparation' '
@@ -58,15 +58,15 @@ while read verb expect cmd args
 do
 	# No width limit applied when statNameWidth is ignored
 	case "$expect" in expect72|expect.6030)
-		test_expect_success "$cmd $verb statNameWidth config with long name" '
+		test_expect_success "$cmd $verb diff.statNameWidth with long name" '
 			git -c diff.statNameWidth=30 $cmd $args >output &&
 			grep " | " output >actual &&
 			test_cmp $expect actual
 		';;
 	esac
 	# Maximum width limit still applied when statNameWidth is ignored
 	case "$expect" in expect.60|expect.6030)
-		test_expect_success "$cmd --stat=width $verb statNameWidth config with long name" '
+		test_expect_success "$cmd --stat=width $verb diff.statNameWidth with long name" '
 			git -c diff.statNameWidth=30 $cmd $args --stat=60 >output &&
 			grep " | " output >actual &&
 			test_cmp $expect actual
@@ -111,19 +111,19 @@ do
 		test_cmp $expect.6030 actual
 	'
 
-	test_expect_success "$cmd --stat-name-width with long name" '
+	test_expect_success "$cmd --stat-name-width=width with long name" '
 		git $cmd $args --stat-name-width=30 >output &&
 		grep " | " output >actual &&
 		test_cmp $expect.6030 actual
 	'
 done <<\EOF
 expect2 format-patch --cover-letter -1 --stdout
 expect diff HEAD^ HEAD --stat
 expect show --stat
 expect log -1 --stat
 EOF
 
-test_expect_success 'preparation for big change tests' '
+test_expect_success 'preparation for big-change tests' '
 	>abcd &&
 	git add abcd &&
 	git commit -m message &&
@@ -139,7 +139,7 @@ cat >expect72 <<'EOF'
  abcd | 1000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  abcd | 1000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 EOF
-test_expect_success "format-patch --cover-letter ignores COLUMNS (big change)" '
+test_expect_success "format-patch --cover-letter ignores COLUMNS with big change" '
 	COLUMNS=200 git format-patch -1 --stdout --cover-letter >output &&
 	grep " | " output >actual &&
 	test_cmp expect72 actual
@@ -159,15 +159,15 @@ cat >expect200-graph <<'EOF'
 EOF
 while read verb expect cmd args
 do
-	test_expect_success "$cmd $verb COLUMNS (big change)" '
+	test_expect_success "$cmd $verb COLUMNS with big change" '
 		COLUMNS=200 git $cmd $args >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect" actual
 	'
 
 	case "$cmd" in diff|show) continue;; esac
 
-	test_expect_success "$cmd --graph $verb COLUMNS (big change)" '
+	test_expect_success "$cmd --graph $verb COLUMNS with big change" '
 		COLUMNS=200 git $cmd $args --graph >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect-graph" actual
@@ -187,15 +187,15 @@ cat >expect40-graph <<'EOF'
 EOF
 while read verb expect cmd args
 do
-	test_expect_success "$cmd $verb not enough COLUMNS (big change)" '
+	test_expect_success "$cmd $verb not enough COLUMNS with big change" '
 		COLUMNS=40 git $cmd $args >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect" actual
 	'
 
 	case "$cmd" in diff|show) continue;; esac
 
-	test_expect_success "$cmd --graph $verb not enough COLUMNS (big change)" '
+	test_expect_success "$cmd --graph $verb not enough COLUMNS with big change" '
 		COLUMNS=40 git $cmd $args --graph >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect-graph" actual
@@ -215,15 +215,15 @@ cat >expect40-graph <<'EOF'
 EOF
 while read verb expect cmd args
 do
-	test_expect_success "$cmd $verb statGraphWidth config" '
+	test_expect_success "$cmd $verb diff.statGraphWidth" '
 		git -c diff.statGraphWidth=26 $cmd $args >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect" actual
 	'
 
 	case "$cmd" in diff|show) continue;; esac
 
-	test_expect_success "$cmd --graph $verb statGraphWidth config" '
+	test_expect_success "$cmd --graph $verb diff.statGraphWidth" '
 		git -c diff.statGraphWidth=26 $cmd $args --graph >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect-graph" actual
@@ -255,33 +255,33 @@ do
 		test_cmp expect actual
 	'
 
-	test_expect_success "$cmd --stat-graph-width with big change" '
+	test_expect_success "$cmd --stat-graph-width=width with big change" '
 		git $cmd $args --stat-graph-width=26 >output &&
 		grep " | " output >actual &&
 		test_cmp expect actual
 	'
 
 	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success "$cmd --stat-width=width --graph with big change" '
 		git $cmd $args --stat-width=40 --graph >output &&
 		grep " | " output >actual &&
 		test_cmp expect-graph actual
 	'
 
-	test_expect_success "$cmd --stat-graph-width --graph with big change" '
+	test_expect_success "$cmd --stat-graph-width=width --graph with big change" '
 		git $cmd $args --stat-graph-width=26 --graph >output &&
 		grep " | " output >actual &&
 		test_cmp expect-graph actual
 	'
 done <<\EOF
 format-patch -1 --stdout
 diff HEAD^ HEAD --stat
 show --stat
 log -1 --stat
 EOF
 
-test_expect_success 'preparation for long filename tests' '
+test_expect_success 'preparation for long-name tests' '
 	cp abcd aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa &&
 	git add aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa &&
 	git commit -m message
@@ -329,15 +329,15 @@ cat >expect200-graph <<'EOF'
 EOF
 while read verb expect cmd args
 do
-	test_expect_success "$cmd $verb COLUMNS (long filename)" '
+	test_expect_success "$cmd $verb COLUMNS with long name" '
 		COLUMNS=200 git $cmd $args >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect" actual
 	'
 
 	case "$cmd" in diff|show) continue;; esac
 
-	test_expect_success "$cmd --graph $verb COLUMNS (long filename)" '
+	test_expect_success "$cmd --graph $verb COLUMNS with long name" '
 		COLUMNS=200 git $cmd $args --graph >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect-graph" actual
@@ -358,41 +358,57 @@ EOF
 while read verb expect cmd args
 do
 	test_expect_success COLUMNS_CAN_BE_1 \
-		"$cmd $verb prefix greater than COLUMNS (big change)" '
+		"$cmd $verb prefix greater than COLUMNS with big change" '
 		COLUMNS=1 git $cmd $args >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect" actual
 	'
 
 	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success COLUMNS_CAN_BE_1 \
-		"$cmd --graph $verb prefix greater than COLUMNS (big change)" '
+		"$cmd --graph $verb prefix greater than COLUMNS with big change" '
 		COLUMNS=1 git $cmd $args --graph >output &&
 		grep " | " output >actual &&
 		test_cmp "$expect-graph" actual
 	'
 done <<\EOF
 ignores expect72 format-patch -1 --stdout
 respects expect1 diff HEAD^ HEAD --stat
 respects expect1 show --stat
 respects expect1 log -1 --stat
 EOF
 
 cat >expect <<'EOF'
  abcd | 1000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 EOF
-test_expect_success 'merge --stat respects COLUMNS (big change)' '
-	git checkout -b branch HEAD^^ &&
+test_expect_success 'merge --stat respects diff.statGraphWidth with big change' '
+	git checkout -b branch1 HEAD^^ &&
+	git -c diff.statGraphWidth=26 merge --stat --no-ff main^ >output &&
+	grep " | " output >actual &&
+	test_cmp expect40 actual
+'
+test_expect_success 'merge --stat respects COLUMNS with big change' '
+	git checkout -b branch2 HEAD^^ &&
 	COLUMNS=100 git merge --stat --no-ff main^ >output &&
 	grep " | " output >actual &&
 	test_cmp expect actual
 '
 
 cat >expect <<'EOF'
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa | 1000 +++++++++++++++++++++++++++++++++++++++
 EOF
-test_expect_success 'merge --stat respects COLUMNS (long filename)' '
+cat >expect.30 <<'EOF'
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaa | 1000 ++++++++++++++++++++++++++++++++++++++++
+EOF
+test_expect_success 'merge --stat respects diff.statNameWidth with long name' '
+	git switch branch1 &&
+	git -c diff.statNameWidth=30 merge --stat --no-ff main >output &&
+	grep " | " output >actual &&
+	test_cmp expect.30 actual
+'
+test_expect_success 'merge --stat respects COLUMNS with long name' '
+	git switch branch2 &&
 	COLUMNS=100 git merge --stat --no-ff main >output &&
 	grep " | " output >actual &&
 	test_cmp expect actual
