diff --git a/libvips/deprecated/vips7compat.c b/libvips/deprecated/vips7compat.c
index aabae8e6..13e5914d 100644
--- a/libvips/deprecated/vips7compat.c
+++ b/libvips/deprecated/vips7compat.c
@@ -55,11 +55,22 @@
  * FILENAME_MAX chars.
  *
  * We look for the ':' splitting the name and mode by searching for the
- * rightmost occurence of the regexp ".[A-Za-z0-9]+:". Example: consider the
- * horror that is
+ * rightmost occurrence of the regexp "\.[A-Za-z0-9]+:". The initial dot can
+ * be missing if there's a dirsep or start of string, meaning this is a
+ * filename without an extension.
+ *
+ * Examples:
  *
  * 	c:\silly:dir:name\fr:ed.tif:jpeg:95,,,,c:\icc\srgb.icc
+ * 	  -> c:\silly:dir:name\fr:ed.tif  jpeg:95,,,,c:\icc\srgb.icc
+ * 	I180:
+ * 	  -> I180 ""
+ * 	c:\silly:
+ * 	  -> c:\silly ""
+ * 	c:\silly
+ * 	  -> c:\silly ""
  *
+ * vips8 handles this in a much better way :( 
  */
 void
 im_filename_split( const char *path, char *name, char *mode )
@@ -74,11 +85,15 @@ im_filename_split( const char *path, char *name, char *mode )
 		if( *p == ':' ) {
 			char *q;
 
+			/* We are skipping back over the file extension,
+			 * isalnum() is probably sufficient.
+			 */
 			for( q = p - 1; isalnum( *q ) && q > name; q -= 1 )
 				;
 
-			if( *q == '.' )
+			if( *q == '.' ) {
 				break;
+			}
 
 			/* All the way back to the start? We probably have a
 			 * filename with no extension, eg. "I180:"
@@ -86,9 +101,11 @@ im_filename_split( const char *path, char *name, char *mode )
 			if( q == name )
 				break;
 
-			/* .. or we could hit a dirsep.
+			/* .. or we could hit a dirsep. Allow win or nix
+			 * separators.
 			 */
-			if( *q == G_DIR_SEPARATOR )
+			if( *q == '/' || 
+				*q == '\\' )
 				break;
 		}
 
@@ -100,6 +117,40 @@ im_filename_split( const char *path, char *name, char *mode )
                 strcpy( mode, "" );
 }
 
+/** 
+ * vips_path_filename7:
+ * @path: path to split
+ *
+ * Return the filename part of a vips7 path. For testing only.
+ */
+char *
+vips_path_filename7( const char *path )
+{
+	char name[FILENAME_MAX];
+	char mode[FILENAME_MAX];
+
+	im_filename_split( path, name, mode );
+
+	return( g_strdup( name ) );
+}
+
+/** 
+ * vips_path_mode7:
+ * @path: path to split
+ *
+ * Return the mode part of a vips7 path. For testing only.
+ */
+char *
+vips_path_mode7( const char *path )
+{
+	char name[FILENAME_MAX];
+	char mode[FILENAME_MAX];
+
+	im_filename_split( path, name, mode );
+
+	return( g_strdup( mode ) );
+}
+
 /* Skip any leading path stuff. Horrible: if this is a filename which came
  * from win32 and we're a *nix machine, it'll have '\\' not '/' as the
  * separator :-(
diff --git a/libvips/include/vips/basic.h b/libvips/include/vips/basic.h
index 8f846531..a0adf4b4 100644
--- a/libvips/include/vips/basic.h
+++ b/libvips/include/vips/basic.h
@@ -66,6 +66,11 @@ typedef enum {
 	VIPS_PRECISION_LAST
 } VipsPrecision;
 
+/* Just for testing.
+ */
+char *vips_path_filename7( const char *path );
+char *vips_path_mode7( const char *path );
+
 #ifdef __cplusplus
 }
 #endif /*__cplusplus*/
diff --git a/test/Makefile.am b/test/Makefile.am
index ee0b0c41..bd82e2ca 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -13,6 +13,7 @@ EXTRA_DIST = \
 	test_colour.py \
 	test_conversion.py \
 	test_convolution.py \
+	test_iofuncs.py \
 	test_create.py \
 	test_foreign.py \
 	test_draw.py \
diff --git a/test/test_all.py b/test/test_all.py
index 3fefe8ef..98fcf747 100755
--- a/test/test_all.py
+++ b/test/test_all.py
@@ -12,6 +12,7 @@ from test_foreign import *
 from test_histogram import *
 from test_morphology import *
 from test_resample import *
+from test_iofuncs import *
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/test/test_iofuncs.py b/test/test_iofuncs.py
new file mode 100755
index 00000000..0f1bba44
--- /dev/null
+++ b/test/test_iofuncs.py
@@ -0,0 +1,61 @@
+#!/usr/bin/python3
+
+from __future__ import division
+import unittest
+import math
+
+#import logging
+#logging.basicConfig(level = logging.DEBUG)
+
+from gi.repository import Vips 
+
+Vips.leak_set(True)
+
+# an expanding zip ... if either of the args is not a list, duplicate it down
+# the other
+def zip_expand(x, y):
+    if isinstance(x, list) and isinstance(y, list):
+        return list(zip(x, y))
+    elif isinstance(x, list):
+        return [[i, y] for i in x]
+    elif isinstance(y, list):
+        return [[x, j] for j in y]
+    else:
+        return [[x, y]]
+
+class TestIofuncs(unittest.TestCase):
+    # test a pair of things which can be lists for approx. equality
+    def assertEqualObjects(self, a, b, msg = ''):
+        #print('assertEqualObjects %s = %s' % (a, b))
+        for x, y in zip_expand(a, b):
+            self.assertEqual(x, y, msg = msg)
+
+    # test the vips7 filename splitter ... this is very fragile and annoying
+    # code with lots of cases
+    def test_split7(self):
+        def split(path):
+            filename7 = Vips.path_filename7(path)
+            mode7 = Vips.path_mode7(path)
+
+            return [filename7, mode7]
+
+        cases = [
+            ["c:\\silly:dir:name\\fr:ed.tif:jpeg:95,,,,c:\\icc\\srgb.icc",
+                ["c:\\silly:dir:name\\fr:ed.tif", 
+                 "jpeg:95,,,,c:\\icc\\srgb.icc"]],
+            ["I180:",
+                ["I180",
+                 ""]],
+            ["c:\\silly:",
+                ["c:\\silly",
+                 ""]],
+            ["c:\\program files\\x:hello",
+                ["c:\\program files\\x",
+                 "hello"]]
+        ]
+            
+        for case in cases:
+            self.assertEqualObjects(split(case[0]), case[1])
+
+if __name__ == '__main__':
+    unittest.main()