diff --git a/lslopt/lslparse.py b/lslopt/lslparse.py
index 7d7edcf..1636ada 100644
--- a/lslopt/lslparse.py
+++ b/lslopt/lslparse.py
@@ -545,6 +545,19 @@ class parser(object):
                 raise EParseUEOF(self)
             raise EParseSyntax(self)
 
+    def does_something(self, blk):
+        """Tell if a list of nodes does something or is just empty statements
+        (a pure combination of ';' and '{}' and '@')
+        """
+        for node in blk:
+            if '@' != node['nt'] != ';':
+                if node['nt'] == '{}':
+                    if self.does_something(node['ch']):
+                        return True
+                else:
+                    return True
+        return False
+
     def Parse_vector_rotation_tail(self):
         """(See Parse_unary_postfix_expression for context)
 
@@ -1682,13 +1695,25 @@ list lazy_list_set(list L, integer i, list v)
             if switchcasedefault is None:
                 if self.errmissingdefault:
                     raise EParseMissingDefault(self)
-                switchcasedefault = brk
-                self.breakstack[-1][2] = True
-            # TODO: Check if this JUMP is necessary
-            # (it won't be if the default label is the next instruction)
-            # This is arguably better done after DCR.
-            prelude.append({'nt':'JUMP', 't':None, 'name':switchcasedefault,
-                'scope':blkscope})
+                # Check if it's worth adding a break. If there's no executable
+                # code, there's no point. However, this check is insufficient.
+                # It misses SEF expressions. For that reason, this is best left
+                # up to a later optimizer that knows about SEF. But we do a
+                # preliminary elimination here.
+                if self.does_something(blk):
+                    switchcasedefault = brk
+                    self.breakstack[-1][2] = True
+            else:
+                # TODO: Keep checking until there's output-generating code.
+                # For example, this isn't optimized due to the semicolon:
+                #    switch(1) { ; default: 1; }
+                if blk and blk[0]['nt'] == '@' and blk[0]['name'] == switchcasedefault:
+                    switchcasedefault = None
+                    del blk[0]
+
+            if switchcasedefault is not None:
+                prelude.append({'nt':'JUMP', 't':None, 'name':switchcasedefault,
+                    'scope':blkscope})
             last = self.breakstack.pop()
             if last[2]:
                 blk.append({'nt':'@', 'name':brk, 'scope':blkscope})