diff --git a/builtin/apply.c b/builtin/apply.c
index 31f873318c3f9ff020688d3ac1aab2d8b54e2757..da6fb355453c1a77d16a3ede38d295f5af8569d9 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -2171,6 +2171,12 @@ static void update_pre_post_images(struct image *preimage,
 		ctx++;
 	}
 
+	if (postlen
+	    ? postlen < new - postimage->buf
+	    : postimage->len < new - postimage->buf)
+		die("BUG: caller miscounted postlen: asked %d, orig = %d, used = %d",
+		    (int)postlen, (int) postimage->len, (int)(new - postimage->buf));
+
 	/* Fix the length of the whole thing */
 	postimage->len = new - postimage->buf;
 	postimage->nr -= reduced;
diff --git a/t/t4138-apply-ws-expansion.sh b/t/t4138-apply-ws-expansion.sh
new file mode 100755
index 0000000000000000000000000000000000000000..0ffe33fbefdc72c664d3914da234f7d4052ed462
--- /dev/null
+++ b/t/t4138-apply-ws-expansion.sh
@@ -0,0 +1,121 @@
+#!/bin/sh
+#
+# Copyright (C) 2015 Kyle J. McKay
+#
+
+test_description='git apply test patches with whitespace expansion.'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	#
+	## create test-N, patchN.patch, expect-N files
+	#
+
+	# test 1
+	printf "\t%s\n" 1 2 3 4 5 6 >before &&
+	printf "\t%s\n" 1 2 3 >after &&
+	printf "%64s\n" a b c >>after &&
+	printf "\t%s\n" 4 5 6 >>after &&
+	git diff --no-index before after |
+		sed -e "s/before/test-1/" -e "s/after/test-1/" >patch1.patch &&
+	printf "%64s\n" 1 2 3 4 5 6 >test-1 &&
+	printf "%64s\n" 1 2 3 a b c 4 5 6 >expect-1 &&
+
+	# test 2
+	printf "\t%s\n" a b c d e f >before &&
+	printf "\t%s\n" a b c >after &&
+	n=10 &&
+	x=1 &&
+	while test $x -lt $n
+	do
+		printf "%63s%d\n" "" $x >>after
+		x=$(( $x + 1 ))
+	done &&
+	printf "\t%s\n" d e f >>after &&
+	git diff --no-index before after |
+		sed -e "s/before/test-2/" -e "s/after/test-2/" >patch2.patch &&
+	printf "%64s\n" a b c d e f >test-2 &&
+	printf "%64s\n" a b c >expect-2 &&
+	x=1 &&
+	while test $x -lt $n
+	do
+		printf "%63s%d\n" "" $x >>expect-2
+		x=$(( $x + 1 ))
+	done &&
+	printf "%64s\n" d e f >>expect-2 &&
+
+	# test 3
+	printf "\t%s\n" a b c d e f >before &&
+	printf "\t%s\n" a b c >after &&
+	n=100 &&
+	x=0 &&
+	while test $x -lt $n
+	do
+		printf "%63s%02d\n" "" $x >>after
+		x=$(( $x + 1 ))
+	done &&
+	printf "\t%s\n" d e f >>after &&
+	git diff --no-index before after |
+	sed -e "s/before/test-3/" -e "s/after/test-3/" >patch3.patch &&
+	printf "%64s\n" a b c d e f >test-3 &&
+	printf "%64s\n" a b c >expect-3 &&
+	x=0 &&
+	while test $x -lt $n
+	do
+		printf "%63s%02d\n" "" $x >>expect-3
+		x=$(( $x + 1 ))
+	done &&
+	printf "%64s\n" d e f >>expect-3 &&
+
+	# test 4
+	>before &&
+	x=0 &&
+	while test $x -lt 50
+	do
+		printf "\t%02d\n" $x >>before
+		x=$(( $x + 1 ))
+	done &&
+	cat before >after &&
+	printf "%64s\n" a b c >>after &&
+	while test $x -lt 100
+	do
+		printf "\t%02d\n" $x >>before
+		printf "\t%02d\n" $x >>after
+		x=$(( $x + 1 ))
+	done &&
+	git diff --no-index before after |
+	sed -e "s/before/test-4/" -e "s/after/test-4/" >patch4.patch &&
+	>test-4 &&
+	x=0 &&
+	while test $x -lt 50
+	do
+		printf "%63s%02d\n" "" $x >>test-4
+		x=$(( $x + 1 ))
+	done &&
+	cat test-4 >expect-4 &&
+	printf "%64s\n" a b c >>expect-4 &&
+	while test $x -lt 100
+	do
+		printf "%63s%02d\n" "" $x >>test-4
+		printf "%63s%02d\n" "" $x >>expect-4
+		x=$(( $x + 1 ))
+	done &&
+
+	git config core.whitespace tab-in-indent,tabwidth=63 &&
+	git config apply.whitespace fix
+
+'
+
+# Note that `patch` can successfully apply all patches when run
+# with the --ignore-whitespace option.
+
+for t in 1 2 3 4
+do
+	test_expect_success 'apply with ws expansion (t=$t)' '
+		git apply patch$t.patch &&
+		test_cmp test-$t expect-$t
+	'
+done
+
+test_done