diff --git a/sub-process.c b/sub-process.c
index 83bf0a0e82e56d..2d5c965169727b 100644
--- a/sub-process.c
+++ b/sub-process.c
@@ -132,17 +132,24 @@ static int handshake_version(struct child_process *process,
 	if (packet_flush_gently(process->in))
 		return error("Could not write flush packet");
 
-	if (!(line = packet_read_line(process->out, NULL)) ||
-	    !skip_prefix(line, welcome_prefix, &p) ||
+	if (packet_read_line_gently(process->out, NULL, &line) < 0)
+		return error("could not read greeting from subprocess '%s'",
+			     process->args.v[0]);
+	if (!line || !skip_prefix(line, welcome_prefix, &p) ||
 	    strcmp(p, "-server"))
 		return error("Unexpected line '%s', expected %s-server",
 			     line ? line : "<flush packet>", welcome_prefix);
-	if (!(line = packet_read_line(process->out, NULL)) ||
-	    !skip_prefix(line, "version=", &p) ||
+	if (packet_read_line_gently(process->out, NULL, &line) < 0)
+		return error("could not read version from subprocess '%s'",
+			     process->args.v[0]);
+	if (!line || !skip_prefix(line, "version=", &p) ||
 	    strtol_i(p, 10, chosen_version))
 		return error("Unexpected line '%s', expected version",
 			     line ? line : "<flush packet>");
-	if ((line = packet_read_line(process->out, NULL)))
+	if (packet_read_line_gently(process->out, NULL, &line) < 0)
+		return error("could not read version flush from subprocess '%s'",
+			     process->args.v[0]);
+	if (line)
 		return error("Unexpected line '%s', expected flush", line);
 
 	/* Check to make sure that the version received is supported */
@@ -171,8 +178,15 @@ static int handshake_capabilities(struct child_process *process,
 	if (packet_flush_gently(process->in))
 		return error("Could not write flush packet");
 
-	while ((line = packet_read_line(process->out, NULL))) {
+	for (;;) {
 		const char *p;
+		int len = packet_read_line_gently(process->out, NULL, &line);
+
+		if (len < 0)
+			return error("could not read capabilities from subprocess '%s'",
+				     process->args.v[0]);
+		if (!line)
+			break;
 		if (!skip_prefix(line, "capability=", &p))
 			continue;
 
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index f0d50d769e9fc5..033b00a364ee7a 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -857,6 +857,23 @@ test_expect_success 'invalid process filter must fail (and not hang!)' '
 	)
 '
 
+test_expect_success 'missing process filter with space in path does not die' '
+	test_config_global filter.protocol.process "/non existent/tool" &&
+	test_config_global filter.protocol.required true &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "*.r filter=protocol" >.gitattributes &&
+
+		cp "$TEST_ROOT/test.o" test.r &&
+		test_must_fail git add . 2>git-stderr.log &&
+		test_grep "clean filter.*protocol.*failed" git-stderr.log
+	)
+'
+
 test_expect_success 'delayed checkout in process filter' '
 	test_config_global filter.a.process "test-tool rot13-filter --log=a.log clean smudge delay" &&
 	test_config_global filter.a.required true &&