diff --git a/fuzzers/034b-cmt-mmcm-pips/fixup_and_group.py b/fuzzers/034b-cmt-mmcm-pips/fixup_and_group.py
index 10e1a008..49fff972 100755
--- a/fuzzers/034b-cmt-mmcm-pips/fixup_and_group.py
+++ b/fuzzers/034b-cmt-mmcm-pips/fixup_and_group.py
@@ -220,9 +220,6 @@ def main():
 
     tags_to_remove = set()
     for tag, bits in segbits.items():
-        if len(bits) == 0:
-            tags_to_remove.add(tag)
-
         if 'REBUF' in tag and 'ACTIVE' not in tag:
             # FIXME: Removing REBUF pips for now.
             tags_to_remove.add(tag)
@@ -232,15 +229,14 @@ def main():
 
     for tag in segbits.keys():
         if tag.endswith("_ACTIVE") and 'FREQ_BB' in tag:
-            if 'FREQ_BB_REBUF' in tag:
-                m = re.search('FREQ_BB_REBUF([0-9])', tag)
-            else:
-                m = re.search('FREQ_BB_NS([0-9])', tag)
-            assert m is not None, tag
-
-            prefix = '.CMT_R_LOWER_B_CLK_FREQ_BB{}'.format(m.group(1))
-            tags_to_mask = [t for t in segbits.keys() if t.endswith(prefix)]
-            mask_out_bits(segbits, segbits[tag], tags_to_mask)
+            for idx in range(4):
+                prefix1 = '.CMT_L_LOWER_B_CLK_FREQ_BB{}'.format(idx)
+                prefix2 = '.CMT_R_LOWER_B_CLK_FREQ_BB{}'.format(idx)
+                tags_to_mask = [
+                    t for t in segbits.keys()
+                    if t.endswith(prefix1) or t.endswith(prefix2)
+                ]
+                mask_out_bits(segbits, segbits[tag], tags_to_mask)
 
     # Find common bits
     bit_groups = find_common_bits_for_tag_groups(segbits, tag_groups)
diff --git a/fuzzers/034b-cmt-mmcm-pips/generate.tcl b/fuzzers/034b-cmt-mmcm-pips/generate.tcl
index 2283ec1b..7491c08e 100644
--- a/fuzzers/034b-cmt-mmcm-pips/generate.tcl
+++ b/fuzzers/034b-cmt-mmcm-pips/generate.tcl
@@ -47,6 +47,116 @@ proc write_used_wires {filename} {
     close $fp
 }
 
+proc load_route {line} {
+    puts "MANROUTE: Line: $line"
+
+    # Parse the line
+    set fields [split $line " "]
+    set tile_name [lindex $fields 0]
+    set site_name [lindex $fields 1]
+    set pin_name  [lindex $fields 2]
+    set route_dir [lindex $fields 3]
+    set wires [lrange $fields 4 end]
+
+    # Get net
+    set tile [get_tiles $tile_name]
+    set site [get_sites -of_objects $tile $site_name]
+    set pin [get_site_pins -of_objects $site "*/$pin_name"]
+    set net [get_nets -quiet -of_objects $pin]
+
+    if {$net eq "" } {
+        puts "MANROUTE: No net for pin $pin_name found! Skipping..."
+        return
+    }
+
+    set source_pin [get_pins -of $net -filter "DIRECTION == OUT"]
+    if { [llength $source_pin] == 0 } {
+        error "Failed to find source pin of net $net"
+    }
+
+    set source_site_pins [get_site_pins -of $source_pin]
+    puts "MANROUTE: Possible site pins for net $net: $source_site_pins"
+
+    # Fixed part read from file
+    set route_list {}
+    if { [string first / $wires] != -1 } {
+        # Route list is just intermediate node and final node, fill it in
+        if { [llength $wires] != 2} {
+            error "Expected only 2 wires, found [llength $wires]"
+        }
+
+        set intermediate_node [get_nodes [lindex $wires 0]]
+        set dest_node [get_nodes -of_objects [get_wires -of_objects $tile "*/[lindex $wires 1]"]]
+        if [catch {find_routing_path -from $intermediate_node -to $dest_node} route_list] {
+            puts "MANROUTE: Failed to find routing path from $intermediate_node to $dest_node for net $net\nError: $route_list"
+            return
+        }
+
+        if { [llength $route_list] == 0 } {
+            puts "MANROUTE: Failed to find routing path from $intermediate_node to $dest_node for net $net"
+            return
+        }
+    } else {
+        foreach wire $wires {
+            lappend route_list [get_nodes -of_objects [get_wires -of_objects $tile "*/$wire"]]
+        }
+    }
+
+    # Complete the route
+    if {$route_dir eq "up"} {
+        set node_to [lindex $route_list 0]
+        set node_from [get_nodes -of_objects [get_site_pins -filter {DIRECTION == OUT} -of_objects $net]]
+
+        set rpart [find_routing_path -from $node_from -to $node_to]
+        if {$rpart eq ""} {
+            puts "MANROUTE: No possible route continuation for net $net"
+            return
+        }
+
+        set route_list [concat [lrange $rpart 0 end-1] $route_list]
+    }
+
+    if {$route_dir eq "down"} {
+        set node_from [lindex $route_list e]
+        set node_to [get_nodes -of_objects [get_site_pins -filter {DIRECTION == IN} -of_objects $net]]
+
+        set rpart [find_routing_path -from $node_from -to $node_to]
+        if {$rpart eq ""} {
+            puts "MANROUTE: No possible route continuation for net $net"
+            return
+        }
+        set route_list [concat $route_list [lrange $rpart 1 end]]
+    }
+
+    # Set the fixed route
+    puts "MANROUTE: Net: $net, Route: $route_list. routing..."
+    regsub -all {{}} $route_list "" route
+    if [catch {set_property FIXED_ROUTE $route $net} result] {
+        puts "MANROUTE: Net $net failed to set FIXED_ROUTE, ripping up...\nError: $result"
+        set_property FIXED_ROUTE "" $net
+        set_property IS_ROUTE_FIXED 0 $net
+        route_design -unroute -nets $net
+    }
+
+    # Route the single net. Needed to detect conflicts when evaluating
+    # other ones
+    puts "Running route design"
+    route_design -quiet -directive Quick -nets $net
+    puts "Done running route design"
+
+    # Check for conflicts.
+    set status [get_property ROUTE_STATUS $net]
+    if {$status ne "ROUTED"} {
+        # Ripup and discard the fixed route.
+        set_property FIXED_ROUTE "" $net
+        route_design -unroute -nets $net
+        puts "MANROUTE: Net $net status $status, ripping up..."
+    } else {
+        set_property IS_ROUTE_FIXED 1 $net
+        puts "MANROUTE: Successful manual route for $net"
+    }
+}
+
 proc load_routes {filename} {
     puts "MANROUTE: Loading routes from $filename"
 
@@ -56,86 +166,7 @@ proc load_routes {filename} {
             continue
         }
 
-        puts "MANROUTE: Line: $line"
-
-        # Parse the line
-        set fields [split $line " "]
-        set tile_name [lindex $fields 0]
-        set site_name [lindex $fields 1]
-        set pin_name  [lindex $fields 2]
-        set route_dir [lindex $fields 3]
-        set wires [lrange $fields 4 end]
-
-        # Get net
-        set tile [get_tiles $tile_name]
-        set site [get_sites -of_objects $tile $site_name]
-        set pin [get_site_pins -of_objects $site "*/$pin_name"]
-        set net [get_nets -quiet -of_objects $pin]
-
-        if {$net eq "" } {
-            puts "MANROUTE: No net for pin $pin_name found! Skipping..."
-            continue
-        }
-
-        # Fixed part read from file
-        set route_list {}
-        foreach wire $wires {
-            lappend route_list [get_nodes -of_objects [get_wires -of_objects $tile "*/$wire"]]
-        }
-
-        # Complete the route
-        if {$route_dir eq "up"} {
-            set node_to [lindex $route_list 0]
-            set node_from [get_nodes -of_objects [get_site_pins -filter {DIRECTION == OUT} -of_objects $net]]
-
-            set rpart [find_routing_path -from $node_from -to $node_to]
-            if {$rpart eq ""} {
-                puts "MANROUTE: No possible route continuation for net $net"
-                continue
-            }
-
-            set route_list [concat [lrange $rpart 0 end-1] $route_list]
-        }
-
-        if {$route_dir eq "down"} {
-            set node_from [lindex $route_list e]
-            set node_to [get_nodes -of_objects [get_site_pins -filter {DIRECTION == IN} -of_objects $net]]
-
-            set rpart [find_routing_path -from $node_from -to $node_to]
-            if {$rpart eq ""} {
-                puts "MANROUTE: No possible route continuation for net $net"
-                continue
-            }
-            set route_list [concat $route_list [lrange $rpart 1 end]]
-        }
-
-        # Set the fixed route
-        puts "MANROUTE: Net: $net, Route: $route_list. routing..."
-        regsub -all {{}} $route_list "" route
-        if [catch {set_property FIXED_ROUTE $route $net} ] {
-            puts "MANROUTE: Net $net failed to set FIXED_ROUTE, ripping up..."
-            set_property FIXED_ROUTE "" $net
-            set_property IS_ROUTE_FIXED 0 $net
-            route_design -unroute -nets $net
-        }
-
-        # Route the single net. Needed to detect conflicts when evaluating
-        # other ones
-        puts "Running route design"
-        route_design -quiet -directive Quick -nets $net
-        puts "Done running route design"
-
-        # Check for conflicts.
-        set status [get_property ROUTE_STATUS $net]
-        if {$status ne "ROUTED"} {
-            # Ripup and discard the fixed route.
-            set_property FIXED_ROUTE "" $net
-            route_design -unroute -nets $net
-            puts "MANROUTE: Net $net status $status, ripping up..."
-        } else {
-            set_property IS_ROUTE_FIXED 1 $net
-            puts "MANROUTE: Successful manual route for $net"
-        }
+        load_route $line
     }
 
     close $fp
diff --git a/fuzzers/034b-cmt-mmcm-pips/tag_groups.txt b/fuzzers/034b-cmt-mmcm-pips/tag_groups.txt
index e69de29b..2b088984 100644
--- a/fuzzers/034b-cmt-mmcm-pips/tag_groups.txt
+++ b/fuzzers/034b-cmt-mmcm-pips/tag_groups.txt
@@ -0,0 +1,11 @@
+CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_L_LOWER_B_CLK_FREQ_BB0 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_L_LOWER_B_CLK_FREQ_BB1 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_L_LOWER_B_CLK_FREQ_BB2 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_L_LOWER_B_CLK_FREQ_BB3 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_L_LOWER_B_CLK_IN3_HCLK CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_L_LOWER_B_CLK_IN3_INT
+
+CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_L_LOWER_B_CLK_FREQ_BB0 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_L_LOWER_B_CLK_FREQ_BB1 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_L_LOWER_B_CLK_FREQ_BB2 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_L_LOWER_B_CLK_FREQ_BB3 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_L_LOWER_B_CLK_IN1_HCLK CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_L_LOWER_B_CLK_IN1_INT
+
+CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_L_LOWER_B_CLK_FREQ_BB0 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_L_LOWER_B_CLK_FREQ_BB1 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_L_LOWER_B_CLK_FREQ_BB2 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_L_LOWER_B_CLK_FREQ_BB3 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_L_LOWER_B_CLK_IN2_HCLK CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_L_LOWER_B_CLK_IN2_INT
+
+CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_R_LOWER_B_CLK_FREQ_BB0 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_R_LOWER_B_CLK_FREQ_BB1 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_R_LOWER_B_CLK_FREQ_BB2 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_R_LOWER_B_CLK_FREQ_BB3 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_R_LOWER_B_CLK_IN3_HCLK CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKFBIN.CMT_R_LOWER_B_CLK_IN3_INT
+
+CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_R_LOWER_B_CLK_FREQ_BB0 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_R_LOWER_B_CLK_FREQ_BB1 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_R_LOWER_B_CLK_FREQ_BB2 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_R_LOWER_B_CLK_FREQ_BB3 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_R_LOWER_B_CLK_IN1_HCLK CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN1.CMT_R_LOWER_B_CLK_IN1_INT
+
+CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_R_LOWER_B_CLK_FREQ_BB0 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_R_LOWER_B_CLK_FREQ_BB1 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_R_LOWER_B_CLK_FREQ_BB2 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_R_LOWER_B_CLK_FREQ_BB3 CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_R_LOWER_B_CLK_IN2_HCLK CMT_LOWER_B.CMT_LR_LOWER_B_MMCM_CLKIN2.CMT_R_LOWER_B_CLK_IN2_INT
diff --git a/fuzzers/034b-cmt-mmcm-pips/top.py b/fuzzers/034b-cmt-mmcm-pips/top.py
index 43b01dc5..5eb06ebb 100644
--- a/fuzzers/034b-cmt-mmcm-pips/top.py
+++ b/fuzzers/034b-cmt-mmcm-pips/top.py
@@ -84,6 +84,20 @@ def find_phasers_for_mmcm(grid, loc):
     return phasers
 
 
+def find_hclk_ref_wires_for_mmcm(grid, loc):
+    tilename = grid.tilename_at_loc((loc[0], loc[1] - 17))
+    gridinfo = grid.gridinfo_at_tilename(tilename)
+
+    assert gridinfo.tile_type in ['HCLK_CMT_L', 'HCLK_CMT']
+
+    # HCLK_CMT_MUX_OUT_FREQ_REF[0-3]
+    wires = []
+    for idx in range(4):
+        wires.append('{}/HCLK_CMT_MUX_OUT_FREQ_REF{}'.format(tilename, idx))
+
+    return wires
+
+
 def gen_sites():
     db = Database(util.get_db_root(), util.get_part())
     grid = db.grid()
@@ -94,11 +108,12 @@ def gen_sites():
         for site_name, site_type in gridinfo.sites.items():
             if site_type in ['MMCME2_ADV']:
                 phasers = find_phasers_for_mmcm(grid, loc)
-                yield tile_name, site_name, phasers
+                hclk_wires = find_hclk_ref_wires_for_mmcm(grid, loc)
+                yield tile_name, site_name, phasers, hclk_wires
 
 
 def get_random_route_from_site_pin(
-        pip_list, tile_name, site_pin, direction, occupied_wires):
+        pip_list, tile_name, site_pin, direction, occupied_wires, hclk_wires):
 
     # A map of MMCM site pins to wires they are connected to.
     pin_to_wire = {
@@ -138,6 +153,9 @@ def get_random_route_from_site_pin(
     # The first wire
     wire = pin_to_wire[tile_type][site_pin]
 
+    if site_pin in ["CLKIN1", "CLKIN2", "CLKFBIN"] and random.random() < .2:
+        return [random.choice(hclk_wires), wire]
+
     # Walk randomly.
     route = []
     while True:
@@ -199,7 +217,7 @@ module top(
     count = 0
     mmcms = sorted(gen_sites(), key=lambda x: x[0])
     random.shuffle(mmcms)
-    for tile, site, phasers in mmcms:
+    for tile, site, phasers, hclk_wires in mmcms:
         in_use = random.randint(0, 2) > 0
         count += 1
 
@@ -219,20 +237,20 @@ module top(
 
             # Sometimes manually randomized route for CLKOUTx conflicts with
             # the verilog design.
-            ('CLKOUT0', 'down'),
-            ('CLKOUT1', 'down'),
-            ('CLKOUT2', 'down'),
-            ('CLKOUT3', 'down'),
-            ('CLKOUT4', 'down'),
-            ('CLKOUT5', 'down'),
-            ('CLKOUT6', 'down'),
+            #('CLKOUT0', 'down'),
+            #('CLKOUT1', 'down'),
+            #('CLKOUT2', 'down'),
+            #('CLKOUT3', 'down'),
+            #('CLKOUT4', 'down'),
+            #('CLKOUT5', 'down'),
+            #('CLKOUT6', 'down'),
         ]
 
         occupied_wires = set()
         for pin, dir in pins:
 
             route = get_random_route_from_site_pin(
-                pip_list, tile, pin, dir, occupied_wires)
+                pip_list, tile, pin, dir, occupied_wires, hclk_wires)
             if route is None:
                 endpoints[pin] = ""
                 continue
@@ -248,11 +266,10 @@ module top(
         # Store them in a random order so the TCL script will try to route
         # them also in the random order.
         lines = []
-        for pin, (
-                route,
-                dir,
-        ) in routes.items():
-
+        pins = sorted(routes.keys())
+        random.shuffle(pins)
+        for pin in pins:
+            (route, dir) = routes[pin]
             route_str = " ".join(route)
             lines.append(
                 '{} {} {} {} {}\n'.format(tile, site, pin, dir, route_str))