diff --git a/music21/musicxml/xmlToM21.py b/music21/musicxml/xmlToM21.py
index 00f2fba35..51b0db657 100644
--- a/music21/musicxml/xmlToM21.py
+++ b/music21/musicxml/xmlToM21.py
@@ -2556,6 +2556,11 @@ def getStaffNumber(mxObjectOrNumber) -> int:
                 pass
             except AttributeError:  # a normal number
                 pass
+            if mxObject.tag in ('staff-layout',
+                                'staff-details',
+                                'clef'):
+                # for this subset of number'ed tags, no number means staff 1
+                return 1
             return NO_STAFF_ASSIGNED
         else:
             return NO_STAFF_ASSIGNED
@@ -6011,13 +6016,17 @@ def handleClef(self, mxClef):
 
         >>> MP = musicxml.xmlToM21.MeasureParser()
         >>> MP.handleClef(mxClef)
-        >>> MP.lastClefs
-        {0: <music21.clef.TrebleClef>}
+        >>> MP.lastClefs[1]
+        <music21.clef.TrebleClef>
+        >>> MP.lastClefs[0]
+        <music21.clef.TrebleClef>
 
         >>> mxClefBC = ET.fromstring('<clef number="2"><sign>F</sign><line>4</line></clef>')
         >>> MP.handleClef(mxClefBC)
         >>> MP.lastClefs[2]
         <music21.clef.BassClef>
+        >>> MP.lastClefs[1]
+        <music21.clef.TrebleClef>
         >>> MP.lastClefs[0]
         <music21.clef.TrebleClef>
         '''