diff --git a/git-gui.sh b/git-gui.sh
index 52b463c45f..a6be30e295 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -170,7 +170,35 @@ proc open {args} {
 	uplevel 1 real_open $args
 }
 
-# Wrap open to sanitize arguments
+# Wrap exec/open to sanitize arguments
+
+# unsafe arguments begin with redirections or the pipe or background operators
+proc is_arg_unsafe {arg} {
+	regexp {^([<|>&]|2>)} $arg
+}
+
+proc make_arg_safe {arg} {
+	if {[is_arg_unsafe $arg]} {
+		set arg [file join . $arg]
+	}
+	return $arg
+}
+
+proc make_arglist_safe {arglist} {
+	set res {}
+	foreach arg $arglist {
+		lappend res [make_arg_safe $arg]
+	}
+	return $res
+}
+
+# executes one command
+# no redirections or pipelines are possible
+# cmd is a list that specifies the command and its arguments
+# calls `exec` and returns its value
+proc safe_exec {cmd} {
+	eval exec [make_arglist_safe $cmd]
+}
 
 proc safe_open_file {filename flags} {
 	# a file name starting with "|" would attempt to run a process
@@ -182,6 +210,8 @@ proc safe_open_file {filename flags} {
 	open $filename $flags
 }
 
+# End exec/open wrappers
+
 ######################################################################
 ##
 ## locate our library
@@ -282,11 +312,11 @@ unset oguimsg
 
 if {[tk windowingsystem] eq "aqua"} {
 	catch {
-		exec osascript -e [format {
+		safe_exec [list osascript -e [format {
 			tell application "System Events"
 				set frontmost of processes whose unix id is %d to true
 			end tell
-		} [pid]]
+		} [pid]]]
 	}
 }
 
@@ -571,7 +601,7 @@ proc _lappend_nice {cmd_var} {
 
 	if {![info exists _nice]} {
 		set _nice [_which nice]
-		if {[catch {exec $_nice git version}]} {
+		if {[catch {safe_exec [list $_nice git version]}]} {
 			set _nice {}
 		} elseif {[is_Windows] && [file dirname $_nice] ne [file dirname $::_git]} {
 			set _nice {}
@@ -667,9 +697,9 @@ proc kill_file_process {fd} {
 
 	catch {
 		if {[is_Windows]} {
-			exec taskkill /pid $process
+			safe_exec [list taskkill /pid $process]
 		} else {
-			exec kill $process
+			safe_exec [list kill $process]
 		}
 	}
 }
diff --git a/lib/diff.tcl b/lib/diff.tcl
index f089fdc46b..cfa8a414d3 100644
--- a/lib/diff.tcl
+++ b/lib/diff.tcl
@@ -226,7 +226,7 @@ proc show_other_diff {path w m cont_info} {
 			$ui_diff insert end \
 				"* [mc "Git Repository (subproject)"]\n" \
 				d_info
-		} elseif {![catch {set type [exec file $path]}]} {
+		} elseif {![catch {set type [safe_exec [list file $path]]}]} {
 			set n [string length $path]
 			if {[string equal -length $n $path $type]} {
 				set type [string range $type $n end]
diff --git a/lib/shortcut.tcl b/lib/shortcut.tcl
index 9be79b2e89..d437ea6933 100644
--- a/lib/shortcut.tcl
+++ b/lib/shortcut.tcl
@@ -30,8 +30,8 @@ proc do_cygwin_shortcut {} {
 	global argv0 _gitworktree oguilib
 
 	if {[catch {
-		set desktop [exec cygpath \
-			--desktop]
+		set desktop [safe_exec [list cygpath \
+			--desktop]]
 		}]} {
 			set desktop .
 	}
@@ -50,14 +50,14 @@ proc do_cygwin_shortcut {} {
 					"CHERE_INVOKING=1 \
 					source /etc/profile; \
 					git gui"}
-				exec /bin/mkshortcut.exe \
+				safe_exec [list /bin/mkshortcut.exe \
 					--arguments $shargs \
 					--desc "git-gui on $repodir" \
 					--icon $oguilib/git-gui.ico \
 					--name $fn \
 					--show min \
 					--workingdir $repodir \
-					/bin/sh.exe
+					/bin/sh.exe]
 			} err]} {
 			error_popup [strcat [mc "Cannot write shortcut:"] "\n\n$err"]
 		}
diff --git a/lib/win32.tcl b/lib/win32.tcl
index db91ab84a5..3aedae2f13 100644
--- a/lib/win32.tcl
+++ b/lib/win32.tcl
@@ -2,11 +2,11 @@
 # Copyright (C) 2007 Shawn Pearce
 
 proc win32_read_lnk {lnk_path} {
-	return [exec cscript.exe \
+	return [safe_exec [list cscript.exe \
 		/E:jscript \
 		/nologo \
 		[file join $::oguilib win32_shortcut.js] \
-		$lnk_path]
+		$lnk_path]]
 }
 
 proc win32_create_lnk {lnk_path lnk_exec lnk_dir} {
@@ -15,12 +15,13 @@ proc win32_create_lnk {lnk_path lnk_exec lnk_dir} {
 	set lnk_args [lrange $lnk_exec 1 end]
 	set lnk_exec [lindex $lnk_exec 0]
 
-	eval [list exec wscript.exe \
+	set cmd [list wscript.exe \
 		/E:jscript \
 		/nologo \
 		[file nativename [file join $oguilib win32_shortcut.js]] \
 		$lnk_path \
 		[file nativename [file join $oguilib git-gui.ico]] \
 		$lnk_dir \
-		$lnk_exec] $lnk_args
+		$lnk_exec]
+	safe_exec [concat $cmd $lnk_args]
 }