diff --git a/gitk-git/gitk b/gitk-git/gitk
index fbd36a76e8..be93011414 100755
--- a/gitk-git/gitk
+++ b/gitk-git/gitk
@@ -406,7 +406,7 @@ proc start_rev_list {view} {
 	if {$revs eq {}} {
 	    return 0
 	}
-	set args [concat $vflags($view) $revs]
+	set args [limit_arg_length [concat $vflags($view) $revs]]
     } else {
 	set args $vorigargs($view)
     }
@@ -10058,7 +10058,8 @@ proc getallcommits {} {
 	}
     }
     if {$ids ne {}} {
-	set fd [open [concat $cmd $ids] r]
+	set cmd [limit_arg_length [concat $cmd $ids]]
+	set fd [open $cmd r]
 	fconfigure $fd -blocking 0
 	incr allcommits
 	nowbusy allcommits
@@ -10068,6 +10069,21 @@ proc getallcommits {} {
     }
 }
 
+# The maximum command line length for the CreateProcess function is 32767 characters, see
+# http://blogs.msdn.com/oldnewthing/archive/2003/12/10/56028.aspx
+# Be a little conservative in case Tcl adds some more stuff to the command line we do not
+# know about and truncate the command line at a SHA1-boundary below 32000 characters.
+proc limit_arg_length {cmd} {
+    if {[tk windowingsystem] == "win32" &&
+       [string length $cmd] > 32000} {
+        set ndx [string last " " $cmd 32000]
+        if {$ndx != -1} {
+            return [string range $cmd 0 $ndx]
+        }
+    }
+    return $cmd
+}
+
 # Since most commits have 1 parent and 1 child, we group strings of
 # such commits into "arcs" joining branch/merge points (BMPs), which
 # are commits that either don't have 1 parent or don't have 1 child.
@@ -12078,7 +12094,6 @@ if { [info exists ::env(GITK_MSGSDIR)] } {
     set gitk_prefix [file dirname [file dirname [file normalize $argv0]]]
     set gitk_libdir [file join $gitk_prefix share gitk lib]
     set gitk_msgsdir [file join $gitk_libdir msgs]
-    unset gitk_prefix
 }
 
 ## Internationalization (i18n) through msgcat and gettext. See
@@ -12433,28 +12448,32 @@ if {[expr {[exec git rev-parse --is-inside-work-tree] == "true"}]} {
 set worktree [exec git rev-parse --show-toplevel]
 setcoords
 makewindow
-catch {
-    image create photo gitlogo      -width 16 -height 16
+if {$::tcl_platform(platform) eq {windows} && [file exists $gitk_prefix/etc/git.ico]} {
+    wm iconbitmap . -default $gitk_prefix/etc/git.ico
+} else {
+    catch {
+        image create photo gitlogo      -width 16 -height 16
 
-    image create photo gitlogominus -width  4 -height  2
-    gitlogominus put #C00000 -to 0 0 4 2
-    gitlogo copy gitlogominus -to  1 5
-    gitlogo copy gitlogominus -to  6 5
-    gitlogo copy gitlogominus -to 11 5
-    image delete gitlogominus
+        image create photo gitlogominus -width  4 -height  2
+        gitlogominus put #C00000 -to 0 0 4 2
+        gitlogo copy gitlogominus -to  1 5
+        gitlogo copy gitlogominus -to  6 5
+        gitlogo copy gitlogominus -to 11 5
+        image delete gitlogominus
 
-    image create photo gitlogoplus  -width  4 -height  4
-    gitlogoplus  put #008000 -to 1 0 3 4
-    gitlogoplus  put #008000 -to 0 1 4 3
-    gitlogo copy gitlogoplus  -to  1 9
-    gitlogo copy gitlogoplus  -to  6 9
-    gitlogo copy gitlogoplus  -to 11 9
-    image delete gitlogoplus
+        image create photo gitlogoplus  -width  4 -height  4
+        gitlogoplus  put #008000 -to 1 0 3 4
+        gitlogoplus  put #008000 -to 0 1 4 3
+        gitlogo copy gitlogoplus  -to  1 9
+        gitlogo copy gitlogoplus  -to  6 9
+        gitlogo copy gitlogoplus  -to 11 9
+        image delete gitlogoplus
 
-    image create photo gitlogo32    -width 32 -height 32
-    gitlogo32 copy gitlogo -zoom 2 2
+        image create photo gitlogo32    -width 32 -height 32
+        gitlogo32 copy gitlogo -zoom 2 2
 
-    wm iconphoto . -default gitlogo gitlogo32
+        wm iconphoto . -default gitlogo gitlogo32
+    }
 }
 # wait for the window to become visible
 tkwait visibility .