diff --git a/sdc-plugin/tests/Makefile b/sdc-plugin/tests/Makefile
index b5f7f96..3d602b7 100644
--- a/sdc-plugin/tests/Makefile
+++ b/sdc-plugin/tests/Makefile
@@ -2,6 +2,10 @@
 # set_false_path - test the set_false_path command
 # set_max_delay - test the set_max_delay command
 # set_clock_groups - test the set_clock_groups command
+# restore_from_json - test clock propagation when design restored from json instead verilog
+# period_check - test if the clock propagation fails if a clock wire is missing the PERIOD attribute
+# waveform_check - test if the WAVEFORM attribute value is correct on wire
+# period_format_check - test if PERIOD attribute value is correct on wire
 
 TESTS = counter \
 	counter2 \
@@ -14,7 +18,8 @@
 	set_clock_groups \
 	restore_from_json \
 	period_check \
-	waveform_check
+	waveform_check \
+	period_format_check
 
 UNIT_TESTS = escaping
 
@@ -34,3 +39,5 @@
 period_check_negative = 1
 waveform_check_verify = true
 waveform_check_negative = 1
+period_format_check_verify = true
+period_format_check_negative = 1
diff --git a/sdc-plugin/tests/period_format_check/period_format_check.tcl b/sdc-plugin/tests/period_format_check/period_format_check.tcl
new file mode 100644
index 0000000..bc613de
--- /dev/null
+++ b/sdc-plugin/tests/period_format_check/period_format_check.tcl
@@ -0,0 +1,17 @@
+yosys -import
+plugin -i sdc
+# Import the commands from the plugins to the tcl interpreter
+yosys -import
+
+read_verilog $::env(DESIGN_TOP).v
+read_verilog -specify -lib -D_EXPLICIT_CARRY +/xilinx/cells_sim.v
+read_verilog -lib +/xilinx/cells_xtra.v
+hierarchy -check -auto-top
+# Start flow after library reading
+synth_xilinx -vpr -flatten -abc9 -nosrl -nodsp -iopad -run prepare:check
+
+# Propagate the clocks
+propagate_clocks
+
+# Write out the SDC file after the clock propagation step
+write_sdc $::env(DESIGN_TOP).sdc
diff --git a/sdc-plugin/tests/period_format_check/period_format_check.v b/sdc-plugin/tests/period_format_check/period_format_check.v
new file mode 100644
index 0000000..e6ab294
--- /dev/null
+++ b/sdc-plugin/tests/period_format_check/period_format_check.v
@@ -0,0 +1,36 @@
+module top((* CLOCK_SIGNAL = "yes", PERIOD = "bad value", WAVEFORM = "0 5" *) input clk,
+        input clk2,
+	input [1:0] in,
+	output [5:0] out );
+
+reg [1:0] cnt = 0;
+wire clk_int_1, clk_int_2;
+IBUF ibuf_proxy(.I(clk), .O(ibuf_proxy_out));
+IBUF ibuf_inst(.I(ibuf_proxy_out), .O(ibuf_out));
+assign clk_int_1 = ibuf_out;
+assign clk_int_2 = clk_int_1;
+
+always @(posedge clk_int_2) begin
+	cnt <= cnt + 1;
+end
+
+middle middle_inst_1(.clk(ibuf_out), .out(out[2]));
+middle middle_inst_2(.clk(clk_int_1), .out(out[3]));
+middle middle_inst_3(.clk(clk_int_2), .out(out[4]));
+middle middle_inst_4(.clk(clk2), .out(out[5]));
+
+assign out[1:0] = {cnt[0], in[0]};
+endmodule
+
+module middle(input clk,
+	output out);
+
+reg [1:0] cnt = 0;
+wire clk_int;
+assign clk_int = clk;
+always @(posedge clk_int) begin
+	cnt <= cnt + 1;
+end
+
+assign out = cnt[0];
+endmodule