diff --git a/svgpathtools/parser.py b/svgpathtools/parser.py
index 955c671..3a49416 100644
--- a/svgpathtools/parser.py
+++ b/svgpathtools/parser.py
@@ -30,11 +30,23 @@ def _check_num_parsed_values(values, allowed):
 
 def _parse_transform_substr(transform_substr):
 
+    transform = np.identity(3)
+
+    # A well-formed transform substring is `type(v1 v2 ...)`. Malformed input
+    # (no/extra parenthesis, or non-numeric values) previously raised a bare
+    # ValueError; degrade to the identity matrix with a warning, like the
+    # unknown-type and wrong-argument-count cases below.
+    if transform_substr.count('(') != 1:
+        warnings.warn('Invalid SVG transform substring: {0}'.format(transform_substr))
+        return transform
+
     type_str, value_str = transform_substr.split('(')
     value_str = value_str.replace(',', ' ')
-    values = list(map(float, filter(None, value_str.split(' '))))
-
-    transform = np.identity(3)
+    try:
+        values = list(map(float, filter(None, value_str.split(' '))))
+    except ValueError:
+        warnings.warn('Invalid SVG transform substring: {0}'.format(transform_substr))
+        return transform
     if 'matrix' in type_str:
         if not _check_num_parsed_values(values, [6]):
             return transform
diff --git a/test/test_parsing.py b/test/test_parsing.py
index cf33b1f..e531abf 100644
--- a/test/test_parsing.py
+++ b/test/test_parsing.py
@@ -249,6 +249,19 @@ def test_transform(self):
                    scale(10 0.5)""")
         ))
 
+    def test_transform_malformed(self):
+        # Malformed transform substrings (non-numeric values, missing or extra
+        # parentheses) used to raise a bare ValueError; they should degrade to
+        # the identity matrix like the unknown-type case.
+        import warnings
+        identity = np.identity(3)
+        for bad in ('matrix(1 x 3 4 5 6)', 'translate(a)', 'scale()',
+                    'rotate(1 2 z)', 'foo(1', 'matrix'):
+            with warnings.catch_warnings():
+                warnings.simplefilter('ignore')
+                tf = svgpathtools.parser.parse_transform(bad)
+            self.assertTrue(np.array_equal(identity, tf))
+
     def test_pathd_init(self):
         path0 = Path('')
         path1 = parse_path("M 100 100 L 300 100 L 200 300 z")