diff --git a/apply.c b/apply.c
index 2b0f8bdab5..c9fb45247d 100644
--- a/apply.c
+++ b/apply.c
@@ -1640,6 +1640,14 @@ static void record_ws_error(struct apply_state *state,
 	    state->squelch_whitespace_errors < state->whitespace_error)
 		return;
 
+	/*
+	 * line[len] for an incomplete line points at the "\n" at the end
+	 * of patch input line, so "%.*s" would drop the last letter on line;
+	 * compensate for it.
+	 */
+	if (result & WS_INCOMPLETE_LINE)
+		len++;
+
 	err = whitespace_error_string(result);
 	if (state->apply_verbosity > verbosity_silent)
 		fprintf(stderr, "%s:%d: %s.\n%.*s\n",
@@ -1794,7 +1802,10 @@ static int parse_fragment(struct apply_state *state,
 		}
 
 		/* eat the "\\ No newline..." as well, if exists */
-		len += skip_len;
+		if (skip_len) {
+			len += skip_len;
+			state->linenr++;
+		}
 	}
 	if (oldlines || newlines)
 		return -1;
diff --git a/t/t4124-apply-ws-rule.sh b/t/t4124-apply-ws-rule.sh
index 485c7d2d12..115a0f8579 100755
--- a/t/t4124-apply-ws-rule.sh
+++ b/t/t4124-apply-ws-rule.sh
@@ -556,4 +556,191 @@ test_expect_success 'whitespace check skipped for excluded paths' '
 	git apply --include=used --stat --whitespace=error <patch
 '
 
+test_expect_success 'check incomplete lines (setup)' '
+	rm -f .gitattributes &&
+	git config core.whitespace incomplete-line
+'
+
+test_expect_success 'incomplete context line (not an error)' '
+	(test_write_lines 1 2 3 4 5 && printf 6) >sample-i &&
+	(test_write_lines 1 2 3 0 5 && printf 6) >sample2-i &&
+	cat sample-i >target &&
+	git add target &&
+	cat sample2-i >target &&
+	git diff-files -p target >patch &&
+
+	cat sample-i >target &&
+	git apply --whitespace=error <patch &&
+	test_cmp sample2-i target &&
+
+	cat sample-i >target &&
+	git apply --whitespace=error --check <patch 2>error &&
+	test_cmp sample-i target &&
+	test_must_be_empty error &&
+
+	cat sample2-i >target &&
+	git apply --whitespace=error -R <patch &&
+	test_cmp sample-i target &&
+
+	cat sample2-i >target &&
+	git apply -R --whitespace=error --check <patch 2>error &&
+	test_cmp sample2-i target &&
+	test_must_be_empty error
+'
+
+test_expect_success 'last line made incomplete (error)' '
+	test_write_lines 1 2 3 4 5 6 >sample &&
+	(test_write_lines 1 2 3 4 5 && printf 6) >sample-i &&
+	cat sample >target &&
+	git add target &&
+	cat sample-i >target &&
+	git diff-files -p target >patch &&
+
+	cat sample >target &&
+	test_must_fail git apply --whitespace=error <patch 2>error &&
+	test_grep "no newline" error &&
+
+	cat sample >target &&
+	test_must_fail git apply --whitespace=error --check <patch 2>actual &&
+	test_cmp sample target &&
+	cat >expect <<-\EOF &&
+	<stdin>:10: no newline at the end of file.
+	6
+	error: 1 line adds whitespace errors.
+	EOF
+	test_cmp expect actual &&
+
+	cat sample-i >target &&
+	git apply --whitespace=error -R <patch &&
+	test_cmp sample target &&
+
+	cat sample-i >target &&
+	git apply --whitespace=error --check -R <patch 2>error &&
+	test_cmp sample-i target &&
+	test_must_be_empty error &&
+
+	cat sample >target &&
+	git apply --whitespace=fix <patch &&
+	test_cmp sample target
+'
+
+test_expect_success 'incomplete line removed at the end (not an error)' '
+	(test_write_lines 1 2 3 4 5 && printf 6) >sample-i &&
+	test_write_lines 1 2 3 4 5 6 >sample &&
+	cat sample-i >target &&
+	git add target &&
+	cat sample >target &&
+	git diff-files -p target >patch &&
+
+	cat sample-i >target &&
+	git apply --whitespace=error <patch &&
+	test_cmp sample target &&
+
+	cat sample-i >target &&
+	git apply --whitespace=error --check <patch 2>error &&
+	test_cmp sample-i target &&
+	test_must_be_empty error &&
+
+	cat sample >target &&
+	test_must_fail git apply --whitespace=error -R <patch 2>error &&
+	test_grep "no newline" error &&
+
+	cat sample >target &&
+	test_must_fail git apply --whitespace=error --check -R <patch 2>actual &&
+	test_cmp sample target &&
+	cat >expect <<-\EOF &&
+	<stdin>:9: no newline at the end of file.
+	6
+	error: 1 line adds whitespace errors.
+	EOF
+	test_cmp expect actual &&
+
+	cat sample >target &&
+	git apply --whitespace=fix -R <patch &&
+	test_cmp sample target
+'
+
+test_expect_success 'incomplete line corrected at the end (not an error)' '
+	(test_write_lines 1 2 3 4 5 && printf 6) >sample-i &&
+	test_write_lines 1 2 3 4 5 7 >sample3 &&
+	cat sample-i >target &&
+	git add target &&
+	cat sample3 >target &&
+	git diff-files -p target >patch &&
+
+	cat sample-i >target &&
+	git apply --whitespace=error <patch &&
+	test_cmp sample3 target &&
+
+	cat sample-i >target &&
+	git apply --whitespace=error --check <patch 2>error &&
+	test_cmp sample-i target &&
+	test_must_be_empty error &&
+
+	cat sample3 >target &&
+	test_must_fail git apply --whitespace=error -R <patch 2>error &&
+	test_grep "no newline" error &&
+
+	cat sample3 >target &&
+	test_must_fail git apply --whitespace=error -R --check <patch 2>actual &&
+	test_cmp sample3 target &&
+	cat >expect <<-\EOF &&
+	<stdin>:9: no newline at the end of file.
+	6
+	error: 1 line adds whitespace errors.
+	EOF
+	test_cmp expect actual &&
+
+	cat sample3 >target &&
+	git apply --whitespace=fix -R <patch &&
+	test_cmp sample target
+'
+
+test_expect_success 'incomplete line modified at the end (error)' '
+	(test_write_lines 1 2 3 4 5 && printf 6) >sample-i &&
+	(test_write_lines 1 2 3 4 5 && printf 7) >sample3-i &&
+	test_write_lines 1 2 3 4 5 6 >sample &&
+	test_write_lines 1 2 3 4 5 7 >sample3 &&
+	cat sample-i >target &&
+	git add target &&
+	cat sample3-i >target &&
+	git diff-files -p target >patch &&
+
+	cat sample-i >target &&
+	test_must_fail git apply --whitespace=error <patch 2>error &&
+	test_grep "no newline" error &&
+
+	cat sample-i >target &&
+	test_must_fail git apply --whitespace=error --check <patch 2>actual &&
+	test_cmp sample-i target &&
+	cat >expect <<-\EOF &&
+	<stdin>:11: no newline at the end of file.
+	7
+	error: 1 line adds whitespace errors.
+	EOF
+	test_cmp expect actual &&
+
+	cat sample3-i >target &&
+	test_must_fail git apply --whitespace=error -R <patch 2>error &&
+	test_grep "no newline" error &&
+
+	cat sample3-i >target &&
+	test_must_fail git apply --whitespace=error --check -R <patch 2>actual &&
+	test_cmp sample3-i target &&
+	cat >expect <<-\EOF &&
+	<stdin>:9: no newline at the end of file.
+	6
+	error: 1 line adds whitespace errors.
+	EOF
+	test_cmp expect actual &&
+
+	cat sample-i >target &&
+	git apply --whitespace=fix <patch &&
+	test_cmp sample3 target &&
+
+	cat sample3-i >target &&
+	git apply --whitespace=fix -R <patch &&
+	test_cmp sample target
+'
+
 test_done
diff --git a/ws.c b/ws.c
index 34a7b4fad2..6cc2466c0c 100644
--- a/ws.c
+++ b/ws.c
@@ -186,6 +186,9 @@ static unsigned ws_check_emit_1(const char *line, int len, unsigned ws_rule,
 	if (trailing_whitespace == -1)
 		trailing_whitespace = len;
 
+	if (!trailing_newline && (ws_rule & WS_INCOMPLETE_LINE))
+		result |= WS_INCOMPLETE_LINE;
+
 	/* Check indentation */
 	for (i = 0; i < trailing_whitespace; i++) {
 		if (line[i] == ' ')
@@ -297,6 +300,17 @@ void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule,
 	int last_space_in_indent = -1;
 	int need_fix_leading_space = 0;
 
+	/*
+	 * Remembering that we need to add '\n' at the end
+	 * is sufficient to fix an incomplete line.
+	 */
+	if (ws_rule & WS_INCOMPLETE_LINE) {
+		if (0 < len && src[len - 1] != '\n') {
+			fixed = 1;
+			add_nl_to_tail = 1;
+		}
+	}
+
 	/*
 	 * Strip trailing whitespace
 	 */