diff --git a/git-gui.sh b/git-gui.sh
index 6cbb36eab..bf6869961 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -912,6 +912,7 @@ set default_config(gui.fontdiff) [font configure font_diff]
 set default_config(gui.maxfilesdisplayed) 5000
 set default_config(gui.usettk) 1
 set default_config(gui.warndetachedcommit) 1
+set default_config(gui.tabsize) 8
 set font_descs {
 	{fontui   font_ui   {mc "Main Font"}}
 	{fontdiff font_diff {mc "Diff/Console Font"}}
diff --git a/lib/diff.tcl b/lib/diff.tcl
index b0a5180af..0d5698621 100644
--- a/lib/diff.tcl
+++ b/lib/diff.tcl
@@ -1,6 +1,19 @@
 # git-gui diff viewer
 # Copyright (C) 2006, 2007 Shawn Pearce
 
+proc apply_tab_size {{firsttab {}}} {
+	global have_tk85 repo_config ui_diff
+
+	set w [font measure font_diff "0"]
+	if {$have_tk85 && $firsttab != 0} {
+		$ui_diff configure -tabs [list [expr {$firsttab * $w}] [expr {($firsttab + $repo_config(gui.tabsize)) * $w}]]
+	} elseif {$have_tk85 || $repo_config(gui.tabsize) != 8} {
+		$ui_diff configure -tabs [expr {$repo_config(gui.tabsize) * $w}]
+	} else {
+		$ui_diff configure -tabs {}
+	}
+}
+
 proc clear_diff {} {
 	global ui_diff current_diff_path current_diff_header
 	global ui_index ui_workdir
@@ -105,6 +118,8 @@ proc show_diff {path w {lno {}} {scroll_pos {}} {callback {}}} {
 
 	set cont_info [list $scroll_pos $callback]
 
+	apply_tab_size 0
+
 	if {[string first {U} $m] >= 0} {
 		merge_load_stages $path [list show_unmerged_diff $cont_info]
 	} elseif {$m eq {_O}} {
@@ -401,7 +416,10 @@ proc read_diff {fd conflict_size cont_info} {
 
 		# -- Automatically detect if this is a 3 way diff.
 		#
-		if {[string match {@@@ *} $line]} {set is_3way_diff 1}
+		if {[string match {@@@ *} $line]} {
+			set is_3way_diff 1
+			apply_tab_size 1
+		}
 
 		if {$::current_diff_inheader} {
 
diff --git a/lib/option.tcl b/lib/option.tcl
index 23c9ae72a..b5b6b2fea 100644
--- a/lib/option.tcl
+++ b/lib/option.tcl
@@ -161,6 +161,7 @@ proc do_options {} {
 		{b gui.warndetachedcommit {mc "Warn before committing to a detached head"}}
 		{s gui.stageuntracked {mc "Staging of untracked files"} {list "yes" "no" "ask"}}
 		{b gui.displayuntracked {mc "Show untracked files"}}
+		{i-1..99 gui.tabsize {mc "Tab spacing"}}
 		} {
 		set type [lindex $option 0]
 		set name [lindex $option 1]