diff --git a/fuzzers/005-tilegrid/generate_iob.tcl b/fuzzers/005-tilegrid/generate_iob.tcl
index 0ea201e0..4b1127f5 100644
--- a/fuzzers/005-tilegrid/generate_iob.tcl
+++ b/fuzzers/005-tilegrid/generate_iob.tcl
@@ -19,11 +19,16 @@ proc loc_iob_old {} {
 
 proc loc_iob {} {
     # Get all possible sites
-    set duts [make_iob_sites]
+    # set duts [make_iob_sites]
+    # set dut_sites [get_sites -of_objects [get_pblocks roi] -filter {SITE_TYPE =~ RAMBFIFO36E1*}]
+    #set duts [get_sites -filter {SITE_TYPE =~ IOB33*}]
+    set duts [get_bels -filter {TYPE =~ PAD}]
+
     # Sort them into CMT columns
     set dut_columns [group_dut_cols $duts 75]
     # Assign one from each
-    return [loc_dut_col_bels $dut_columns {di[} {]} ]
+    write_checkpoint -force tmp.dcp
+    return [loc_dut_col_bels $dut_columns {di_bufs[} {].ibuf} ]
 }
 
 proc write_iob { selected_iobs } {
diff --git a/fuzzers/005-tilegrid/top.v b/fuzzers/005-tilegrid/top.v
index 0d321e3f..3f9bb6ce 100644
--- a/fuzzers/005-tilegrid/top.v
+++ b/fuzzers/005-tilegrid/top.v
@@ -15,6 +15,14 @@ module top(input clk, stb, [DIN_N-1:0] di, output do);
 	parameter integer DIN_N = `N_DI;
 	parameter integer DOUT_N = `N_LUT + `N_BRAM;
 
+	wire [DIN_N-1:0] di_buf;
+	genvar i;
+	generate
+		for (i = 0; i < `N_LUT; i = i+1) begin:di_bufs
+		    IBUF ibuf(.I(di[i]), .O(di_buf[i]));
+		end
+	endgenerate
+
 	reg [DIN_N-1:0] din;
 	wire [DOUT_N-1:0] dout;
 
@@ -22,7 +30,7 @@ module top(input clk, stb, [DIN_N-1:0] di, output do);
 	reg [DOUT_N-1:0] dout_shr;
 
 	always @(posedge clk) begin
-		din_shr <= {din_shr, di};
+		din_shr <= {din_shr, di_buf};
 		dout_shr <= {dout_shr, din_shr[DIN_N-1]};
 		if (stb) begin
 			din <= din_shr;
@@ -34,7 +42,7 @@ module top(input clk, stb, [DIN_N-1:0] di, output do);
 
 	roi roi (
 		.clk(clk),
-		.din(din),
+		.din(din[7:0]),
 		.dout(dout)
 	);
 endmodule
diff --git a/fuzzers/005-tilegrid/util.tcl b/fuzzers/005-tilegrid/util.tcl
index 523678e4..e43b3eea 100644
--- a/fuzzers/005-tilegrid/util.tcl
+++ b/fuzzers/005-tilegrid/util.tcl
@@ -48,16 +48,18 @@ proc loc_dut_col_bels { dut_columns cellpre cellpost } {
     set dut_index 0
 
     dict for {column duts_in_column} $dut_columns {
-        set selected_dut_bel_str [min_ysite $duts_in_column]
-        set selected_dut_bel [get_bels $selected_dut_bel_str]
-        set selected_dut_site [get_sites -of_objects $selected_dut_bel]
+        set sel_bel_str [min_ysite $duts_in_column]
+        set sel_bel [get_bels $sel_bel_str]
+        if {"$sel_bel" == ""} {error "Bad bel $sel_bel from bel str $sel_bel_str"}
+        set sel_site [get_sites -of_objects $sel_bel]
+        if {"$sel_site" == ""} {error "Bad site $sel_site from bel $sel_bel"}
 
         set cell [get_cells $cellpre$dut_index$cellpost]
-        puts "LOCing cell $cell to site $selected_dut_site (from bel $selected_dut_bel)"
-        set_property LOC $selected_dut_site $cell
+        puts "LOCing cell $cell to site $sel_site (from bel $sel_bel)"
+        set_property LOC $sel_site $cell
 
         set dut_index [expr $dut_index + 1]
-        lappend ret_bels $selected_dut_bel
+        lappend ret_bels $sel_bel
     }
 
     return $ret_bels