diff --git a/db/ops/update.cpp b/db/ops/update.cpp
index b4550c27953..26787f3e705 100644
--- a/db/ops/update.cpp
+++ b/db/ops/update.cpp
@@ -1061,7 +1061,7 @@ namespace mongo {
         debug.updateobj = updateobj;
 
         // idea with these here it to make them loop invariant for multi updates, and thus be a bit faster for that case
-        // The pointers may be left invalid on a failed yield recovery.
+        // The pointers may be left invalid on a failed or terminal yield recovery.
         NamespaceDetails *d = nsdetails(ns); // can be null if an upsert...
         NamespaceDetailsTransient *nsdt = &NamespaceDetailsTransient::get_w(ns);
 
diff --git a/dbtests/basictests.cpp b/dbtests/basictests.cpp
index 54372cece23..d9ddf7c9ced 100644
--- a/dbtests/basictests.cpp
+++ b/dbtests/basictests.cpp
@@ -411,6 +411,21 @@ namespace BasicTests {
             ASSERT_EQUALS( -1 , lexNumCmp( "a.b.c.d0" , "a.b.c.d00" ) );
             ASSERT_EQUALS( 1 , lexNumCmp( "a.b.c.0.y" , "a.b.c.00.x" ) );
             
+            ASSERT_EQUALS( -1, lexNumCmp( "a", "a-" ) );
+            ASSERT_EQUALS( 1, lexNumCmp( "a-", "a" ) );
+            ASSERT_EQUALS( 0, lexNumCmp( "a-", "a-" ) );
+
+            ASSERT_EQUALS( -1, lexNumCmp( "a", "a-c" ) );
+            ASSERT_EQUALS( 1, lexNumCmp( "a-c", "a" ) );
+            ASSERT_EQUALS( 0, lexNumCmp( "a-c", "a-c" ) );
+
+            ASSERT_EQUALS( 1, lexNumCmp( "a-c.t", "a.t" ) );
+            ASSERT_EQUALS( -1, lexNumCmp( "a.t", "a-c.t" ) );
+            ASSERT_EQUALS( 0, lexNumCmp( "a-c.t", "a-c.t" ) );
+
+            ASSERT_EQUALS( 1, lexNumCmp( "ac.t", "a.t" ) );
+            ASSERT_EQUALS( -1, lexNumCmp( "a.t", "ac.t" ) );
+            ASSERT_EQUALS( 0, lexNumCmp( "ac.t", "ac.t" ) );            
         }
     };
 
diff --git a/jstests/updateg.js b/jstests/updateg.js
new file mode 100644
index 00000000000..f8d452f71b2
--- /dev/null
+++ b/jstests/updateg.js
@@ -0,0 +1,17 @@
+// SERVER-3370 check modifiers with field name characters comparing less than '.' character.
+
+t = db.jstests_updateg;
+
+t.drop();
+t.update({}, { '$inc' : { 'all.t' : 1, 'all-copy.t' : 1 }}, true);
+assert.eq( 1, t.count( {all:{t:1},'all-copy':{t:1}} ) );
+
+t.drop();
+t.save({ 'all' : {}, 'all-copy' : {}});
+t.update({}, { '$inc' : { 'all.t' : 1, 'all-copy.t' : 1 }});
+assert.eq( 1, t.count( {all:{t:1},'all-copy':{t:1}} ) );
+
+t.drop();
+t.save({ 'all11' : {}, 'all2' : {}});
+t.update({}, { '$inc' : { 'all11.t' : 1, 'all2.t' : 1 }});
+assert.eq( 1, t.count( {all11:{t:1},'all2':{t:1}} ) );
diff --git a/util/stringutils.h b/util/stringutils.h
index bab9f608f7e..93598aa520b 100644
--- a/util/stringutils.h
+++ b/util/stringutils.h
@@ -40,7 +40,11 @@ namespace mongo {
         return string(copy);
     }
 
-    // for convenience, '{' is greater than anything and stops number parsing
+    /**
+     * Non numeric characters are compared lexicographically; numeric substrings
+     * are compared numerically; dots separate ordered comparable subunits.
+     * For convenience, character 255 is greater than anything else.
+     */
     inline int lexNumCmp( const char *s1, const char *s2 ) {
         //cout << "START : " << s1 << "\t" << s2 << endl;
 
@@ -48,6 +52,18 @@ namespace mongo {
         
         while( *s1 && *s2 ) {
 
+            bool d1 = ( *s1 == '.' );
+            bool d2 = ( *s2 == '.' );
+            if ( d1 && !d2 )
+             	return -1;
+            if ( d2 && !d1 )
+             	return 1;
+            if ( d1 && d2 ) {
+             	++s1; ++s2;
+                startWord = true;
+                continue;
+            }
+            
             bool p1 = ( *s1 == (char)255 );
             bool p2 = ( *s2 == (char)255 );
             //cout << "\t\t " << p1 << "\t" << p2 << endl;
@@ -64,7 +80,6 @@ namespace mongo {
                 if ( startWord ) {
                     while ( *s1 == '0' ) s1++;
                     while ( *s2 == '0' ) s2++;
-                    startWord = false;
                 }
 
                 char * e1 = (char*)s1;
@@ -94,6 +109,7 @@ namespace mongo {
                 // otherwise, the numbers are equal
                 s1 = e1;
                 s2 = e2;
+                startWord = false;
                 continue;
             }
             
@@ -109,11 +125,8 @@ namespace mongo {
             if ( *s2 > *s1 )
                 return -1;
             
-            if ( *s1 == '.' )
-                startWord = true;
-            else
-                startWord = false;
             s1++; s2++;
+            startWord = false;
         }
 
         if ( *s1 )