diff --git a/src/varint.c b/src/varint.c
index 2f868607c..beac8c709 100644
--- a/src/varint.c
+++ b/src/varint.c
@@ -36,7 +36,7 @@ int git_encode_varint(unsigned char *buf, size_t bufsize, uintmax_t value)
 	while (value >>= 7)
 		varint[--pos] = 128 | (--value & 127);
 	if (buf) {
-		if (bufsize < pos)
+		if (bufsize < (sizeof(varint) - pos))
 			return -1;
 		memcpy(buf, varint + pos, sizeof(varint) - pos);
 	}
diff --git a/tests/core/encoding.c b/tests/core/encoding.c
index 7d91720f4..a677afe2e 100644
--- a/tests/core/encoding.c
+++ b/tests/core/encoding.c
@@ -29,6 +29,9 @@ void test_core_encoding__encode(void)
 	cl_assert(git_encode_varint(buf, 100, 65) == 1);
 	cl_assert(buf[0] == 'A');
 
+	cl_assert(git_encode_varint(buf, 1, 1) == 1);
+	cl_assert(!memcmp(buf, "\x01", 1));
+
 	cl_assert(git_encode_varint(buf, 100, 267869656) == 4);
 	cl_assert(!memcmp(buf, "\xfe\xdc\xbaX", 4));