diff --git a/src/bs_size.c b/src/bs_size.c
index cda12f3..b1fb5a4 100644
--- a/src/bs_size.c
+++ b/src/bs_size.c
@@ -829,7 +829,8 @@ char* bs_size_convert_to (const BSSize size, BSUnit unit, BSError **error) {
 
 /**
  * bs_size_human_readable:
- * @min_unit: the smallest unit the returned representation should use
+ * @min_unit: the smallest unit the returned representation should use.
+ *            Values outside the binary unit range are treated as #BS_BUNIT_B.
  * @max_places: maximum number of decimal places the representation should use
  * @xlate: whether to try to translate the representation or not
  *
@@ -853,7 +854,7 @@ char* bs_size_human_readable (const BSSize size, BSBunit min_unit, int max_place
     mpf_init2 (cur_val, BS_FLOAT_PREC_BITS);
     mpf_set_z (cur_val, size->bytes);
 
-    if (min_unit == BS_BUNIT_UNDEF)
+    if (min_unit < BS_BUNIT_B || min_unit > BS_BUNIT_YiB)
         min_unit = BS_BUNIT_B;
 
     sign = mpf_sgn (cur_val);
diff --git a/tests/lbs_py_override_unittest.py b/tests/lbs_py_override_unittest.py
index d4d38ea..b803f80 100755
--- a/tests/lbs_py_override_unittest.py
+++ b/tests/lbs_py_override_unittest.py
@@ -305,6 +305,15 @@ def testConvertTo(self):
 
         locale.setlocale(locale.LC_ALL,'en_US.UTF-8')
 
+    def testHumanReadableDecimalMinUnit(self):
+        for spec in ("0 B", "1.5 KiB", "-1.5 KiB"):
+            size = Size(spec)
+            for xlate in (False, True):
+                expected = size.human_readable(xlate=xlate)
+                for min_unit in ("KB", "MB"):
+                    with self.subTest(spec=spec, min_unit=min_unit, xlate=xlate):
+                        self.assertEqual(size.human_readable(min_unit, xlate=xlate), expected)
+
     def testRoundToNearest(self):
         size = Size("1.5 KiB")
         conv = size.round_to_nearest(Size("1 KiB"), rounding=ROUND_UP)
diff --git a/tests/libbytesize_unittest.py b/tests/libbytesize_unittest.py
index e958866..5b4412d 100755
--- a/tests/libbytesize_unittest.py
+++ b/tests/libbytesize_unittest.py
@@ -9,7 +9,7 @@
 
 from locale_utils import get_avail_locales, missing_locales, requires_locales
 
-from bytesize import KiB, MB, GiB, ROUND_UP, ROUND_DOWN, ROUND_HALF_UP, OverflowError, InvalidSpecError
+from bytesize import B, KiB, MB, GiB, YiB, ROUND_UP, ROUND_DOWN, ROUND_HALF_UP, OverflowError, InvalidSpecError
 
 # SizeStruct is part of the 'private' API and needs to be imported differently
 # when running from locally build tree and when using installed library
@@ -423,6 +423,12 @@ def testGetBytesStr(self):
     #enddef
 
     def testHumanReadable(self):
+        strSizeStruct = SizeStruct.new_from_str("1.5 KiB").human_readable(B, 2, False)
+        self.assertEqual(strSizeStruct, "1.5 KiB")
+
+        strSizeStruct = SizeStruct.new_from_str("1.5 YiB").human_readable(YiB, 2, False)
+        self.assertEqual(strSizeStruct, "1.5 YiB")
+
         strSizeStruct = SizeStruct.new_from_str("12 KiB").human_readable(KiB, 2, False)
         self.assertEqual(strSizeStruct, "12 KiB")
 
@@ -447,6 +453,15 @@ def testHumanReadable(self):
         self.assertEqual(SizeStruct.new_from_str(strSizeStruct).get_bytes(), (100 * 1024**3, 1))
     #enddef
 
+    def testHumanReadableInvalidMinUnit(self):
+        for spec in ("0 B", "1.5 KiB", "-1.5 KiB"):
+            size = SizeStruct.new_from_str(spec)
+            for xlate in (False, True):
+                expected = size.human_readable(B, 2, xlate)
+                for min_unit in (9, -1, 10, 21, 100):
+                    with self.subTest(spec=spec, min_unit=min_unit, xlate=xlate):
+                        self.assertEqual(size.human_readable(min_unit, 2, xlate), expected)
+
     @requires_locales({'cs_CZ.UTF-8'})
     def testHumanReadableLocale(self):
         locale.setlocale(locale.LC_ALL, 'cs_CZ.UTF-8')