diff --git a/pywb/cdx/cdxops.py b/pywb/cdx/cdxops.py
index 18c420c5..63f5546f 100644
--- a/pywb/cdx/cdxops.py
+++ b/pywb/cdx/cdxops.py
@@ -179,12 +179,13 @@ def cdx_filter(cdx_iter, filter_strings):
             if string.startswith('='):
                 string = string[1:]
                 self.compare_func = self.exact
-            # contains match
+            # regex match
             elif string.startswith('~'):
                 string = string[1:]
-                self.compare_func = self.contains
-            else:
                 self.compare_func = self.regex
+            # contains match
+            else:
+                self.compare_func = self.contains
 
             parts = string.split(':', 1)
             # no field set, apply filter to entire cdx
diff --git a/pywb/cdx/test/test_cdxops.py b/pywb/cdx/test/test_cdxops.py
index 8c550ece..4594173e 100644
--- a/pywb/cdx/test/test_cdxops.py
+++ b/pywb/cdx/test/test_cdxops.py
@@ -45,8 +45,32 @@ NotFoundException: No Captures found for: http://iana.org/dont_have_this
 Traceback (most recent call last):
 NotFoundException: No Captures found for: http://iana.org/dont_have_this
 
-# Filter cdx (default: regex)
->>> cdx_ops_test(url = 'http://iana.org/domains', matchType = 'prefix', filter = ['mimetype:text/html'])
+# Filter cdx (default: contains)
+>>> cdx_ops_test(url = 'http://iana.org/domains', matchType = 'prefix', filter = ['mimetype:html'])
+org,iana)/domains 20140126200825 http://www.iana.org/domains text/html 200 7UPSCLNWNZP33LGW6OJGSF2Y4CDG4ES7 - - 2912 610534 iana.warc.gz
+org,iana)/domains/arpa 20140126201248 http://www.iana.org/domains/arpa text/html 200 QOFZZRN6JIKAL2JRL6ZC2VVG42SPKGHT - - 2939 759039 iana.warc.gz
+org,iana)/domains/idn-tables 20140126201127 http://www.iana.org/domains/idn-tables text/html 200 HNCUFTJMOQOGAEY6T56KVC3T7TVLKGEW - - 8118 715878 iana.warc.gz
+org,iana)/domains/int 20140126201239 http://www.iana.org/domains/int text/html 200 X32BBNNORV4SPEHTQF5KI5NFHSKTZK6Q - - 2482 746788 iana.warc.gz
+org,iana)/domains/reserved 20140126201054 http://www.iana.org/domains/reserved text/html 200 R5AAEQX5XY5X5DG66B23ODN5DUBWRA27 - - 3573 701457 iana.warc.gz
+org,iana)/domains/root 20140126200912 http://www.iana.org/domains/root text/html 200 YWA2R6UVWCYNHBZJKBTPYPZ5CJWKGGUX - - 2691 657746 iana.warc.gz
+org,iana)/domains/root/db 20140126200927 http://www.iana.org/domains/root/db/ text/html 302 3I42H3S6NNFQ2MSVX7XZKYAYSCX5QBYJ - - 446 671278 iana.warc.gz
+org,iana)/domains/root/db 20140126200928 http://www.iana.org/domains/root/db text/html 200 DHXA725IW5VJJFRTWBQT6BEZKRE7H57S - - 18365 672225 iana.warc.gz
+org,iana)/domains/root/servers 20140126201227 http://www.iana.org/domains/root/servers text/html 200 AFW34N3S4NK2RJ6QWMVPB5E2AIUETAHU - - 3137 733840 iana.warc.gz
+
+# Filter cdx (regex)
+>>> cdx_ops_test(url = 'http://iana.org/domains', matchType = 'prefix', filter = ['~mimetype:.*/html$'])
+org,iana)/domains 20140126200825 http://www.iana.org/domains text/html 200 7UPSCLNWNZP33LGW6OJGSF2Y4CDG4ES7 - - 2912 610534 iana.warc.gz
+org,iana)/domains/arpa 20140126201248 http://www.iana.org/domains/arpa text/html 200 QOFZZRN6JIKAL2JRL6ZC2VVG42SPKGHT - - 2939 759039 iana.warc.gz
+org,iana)/domains/idn-tables 20140126201127 http://www.iana.org/domains/idn-tables text/html 200 HNCUFTJMOQOGAEY6T56KVC3T7TVLKGEW - - 8118 715878 iana.warc.gz
+org,iana)/domains/int 20140126201239 http://www.iana.org/domains/int text/html 200 X32BBNNORV4SPEHTQF5KI5NFHSKTZK6Q - - 2482 746788 iana.warc.gz
+org,iana)/domains/reserved 20140126201054 http://www.iana.org/domains/reserved text/html 200 R5AAEQX5XY5X5DG66B23ODN5DUBWRA27 - - 3573 701457 iana.warc.gz
+org,iana)/domains/root 20140126200912 http://www.iana.org/domains/root text/html 200 YWA2R6UVWCYNHBZJKBTPYPZ5CJWKGGUX - - 2691 657746 iana.warc.gz
+org,iana)/domains/root/db 20140126200927 http://www.iana.org/domains/root/db/ text/html 302 3I42H3S6NNFQ2MSVX7XZKYAYSCX5QBYJ - - 446 671278 iana.warc.gz
+org,iana)/domains/root/db 20140126200928 http://www.iana.org/domains/root/db text/html 200 DHXA725IW5VJJFRTWBQT6BEZKRE7H57S - - 18365 672225 iana.warc.gz
+org,iana)/domains/root/servers 20140126201227 http://www.iana.org/domains/root/servers text/html 200 AFW34N3S4NK2RJ6QWMVPB5E2AIUETAHU - - 3137 733840 iana.warc.gz
+
+# Filter cdx (regex)
+>>> cdx_ops_test(url = 'http://iana.org/domains', matchType = 'prefix', filter = ['=mimetype:text/html'])
 org,iana)/domains 20140126200825 http://www.iana.org/domains text/html 200 7UPSCLNWNZP33LGW6OJGSF2Y4CDG4ES7 - - 2912 610534 iana.warc.gz
 org,iana)/domains/arpa 20140126201248 http://www.iana.org/domains/arpa text/html 200 QOFZZRN6JIKAL2JRL6ZC2VVG42SPKGHT - - 2939 759039 iana.warc.gz
 org,iana)/domains/idn-tables 20140126201127 http://www.iana.org/domains/idn-tables text/html 200 HNCUFTJMOQOGAEY6T56KVC3T7TVLKGEW - - 8118 715878 iana.warc.gz
@@ -64,8 +88,8 @@ org,iana)/_css/2013.1/screen.css 20140126200625 http://www.iana.org/_css/2013.1/
 >>> cdx_ops_test(url = 'http://iana.org/_css/2013.1/screen.css', filter = 'status:200')
 org,iana)/_css/2013.1/screen.css 20140126200625 http://www.iana.org/_css/2013.1/screen.css text/css 200 BUAEPXZNN44AIX3NLXON4QDV6OY2H5QD - - 8754 41238 iana.warc.gz
 
-# Filter -- no field specified, match regex on entire line
->>> cdx_ops_test(url = 'http://iana.org/_css/2013.1/screen.css', filter = '~screen.css 20140126200625')
+# Filter -- no field specified, check whether filter query contained in entire line
+>>> cdx_ops_test(url = 'http://iana.org/_css/2013.1/screen.css', filter = 'screen.css 20140126200625')
 org,iana)/_css/2013.1/screen.css 20140126200625 http://www.iana.org/_css/2013.1/screen.css text/css 200 BUAEPXZNN44AIX3NLXON4QDV6OY2H5QD - - 8754 41238 iana.warc.gz
 
 # Filter -- no such field, no matches
@@ -85,12 +109,23 @@ com,example)/ 20140127171200 http://example.com text/html 200 B2LTWWPUOYAH7UIPQ7
 com,example)/ 20140127171251 http://example.com warc/revisit - B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 553 11875 dupes.warc.gz
 
 # Filter contains
->>> cdx_ops_test(url = 'http://example.com', sources = [test_cdx_dir], matchType = 'prefix', filter = '~urlkey:example=1')
+>>> cdx_ops_test(url = 'http://example.com', sources = [test_cdx_dir], matchType = 'prefix', filter = 'urlkey:example=1')
 com,example)/?example=1 20140103030321 http://example.com?example=1 text/html 200 B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 1043 333 example.warc.gz
 com,example)/?example=1 20140103030341 http://example.com?example=1 warc/revisit - B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 553 1864 example.warc.gz
 
 # Filter contains invert
->>> cdx_ops_test(url = 'http://example.com', sources = [test_cdx_dir], matchType = 'prefix', filter = '!~urlkey:example=')
+>>> cdx_ops_test(url = 'http://example.com', sources = [test_cdx_dir], matchType = 'prefix', filter = '!urlkey:example=')
+com,example)/ 20130729195151 http://test@example.com/ warc/revisit - B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 591 355 example-url-agnostic-revisit.warc.gz
+com,example)/ 20140127171200 http://example.com text/html 200 B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 1046 334 dupes.warc.gz
+com,example)/ 20140127171251 http://example.com warc/revisit - B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 553 11875 dupes.warc.gz
+
+# Filter regex
+>>> cdx_ops_test(url = 'http://example.com', sources = [test_cdx_dir], matchType = 'prefix', filter = '~urlkey:.*example=1$')
+com,example)/?example=1 20140103030321 http://example.com?example=1 text/html 200 B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 1043 333 example.warc.gz
+com,example)/?example=1 20140103030341 http://example.com?example=1 warc/revisit - B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 553 1864 example.warc.gz
+
+# Filter regex invert
+>>> cdx_ops_test(url = 'http://example.com', sources = [test_cdx_dir], matchType = 'prefix', filter = '!~urlkey:.*example=[0-9]$')
 com,example)/ 20130729195151 http://test@example.com/ warc/revisit - B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 591 355 example-url-agnostic-revisit.warc.gz
 com,example)/ 20140127171200 http://example.com text/html 200 B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 1046 334 dupes.warc.gz
 com,example)/ 20140127171251 http://example.com warc/revisit - B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A - - 553 11875 dupes.warc.gz