diff --git a/src/calibre/devices/prs505/driver.py b/src/calibre/devices/prs505/driver.py
index f73bdbc44e..3e46e46cde 100644
--- a/src/calibre/devices/prs505/driver.py
+++ b/src/calibre/devices/prs505/driver.py
@@ -32,9 +32,9 @@ class PRS505(CLI, Device):
     WINDOWS_CARD_A_MEM = re.compile(r'PRS-505/\S+:MS')
     WINDOWS_CARD_B_MEM = re.compile(r'PRS-505/\S+:SD')
 
-    OSX_MAIN_MEM   = re.compile(r'Sony PRS-505/\S+ Media')
-    OSX_CARD_A_MEM = re.compile(r'Sony PRS-505/\S+:MS Media')
-    OSX_CARD_B_MEM = re.compile(r'Sony PRS-505/\S+:SD')
+    OSX_MAIN_MEM   = re.compile(r'Sony PRS-505/[^:]+ Media')
+    OSX_CARD_A_MEM = re.compile(r'Sony PRS-505/[^:]+:MS Media')
+    OSX_CARD_B_MEM = re.compile(r'Sony PRS-505/[^:]+:SD Media')
 
     MAIN_MEMORY_VOLUME_LABEL  = 'Sony Reader Main Memory'
     STORAGE_CARD_VOLUME_LABEL = 'Sony Reader Storage Card'
diff --git a/src/calibre/devices/usbms/device.py b/src/calibre/devices/usbms/device.py
index 619753d685..d34e8aa676 100644
--- a/src/calibre/devices/usbms/device.py
+++ b/src/calibre/devices/usbms/device.py
@@ -306,11 +306,11 @@ class Device(DeviceConfig, DevicePlugin):
                     break
 
         for i, line in enumerate(lines):
-            if self.check_ioreg_line(line, self.OSX_MAIN_MEM):
+            if 'main' not in names and self.check_ioreg_line(line, self.OSX_MAIN_MEM):
                 get_dev_node(lines[i+1:], 'main')
-            if self.check_ioreg_line(line, self.OSX_CARD_A_MEM):
+            if 'carda' not in names and self.check_ioreg_line(line, self.OSX_CARD_A_MEM):
                 get_dev_node(lines[i+1:], 'carda')
-            if self.check_ioreg_line(line, self.OSX_CARD_B_MEM):
+            if 'cardb' not in names and self.check_ioreg_line(line, self.OSX_CARD_B_MEM):
                 get_dev_node(lines[i+1:], 'cardb')
             if len(names.keys()) == 3:
                 break