diff --git a/spi_master.v b/spi_master.v
index 0ea7e0b..82463c2 100644
--- a/spi_master.v
+++ b/spi_master.v
@@ -225,3 +225,4 @@ always @ (posedge clk) begin
 end
 
 endmodule
+`undefineall
diff --git a/spi_master_ss_template.v b/spi_master_ss_template.v
index 8b3d0e7..fff9d08 100644
--- a/spi_master_ss_template.v
+++ b/spi_master_ss_template.v
@@ -120,3 +120,4 @@ always @ (posedge clk) begin
 end
 
 endmodule
+`undefineall
diff --git a/spi_slave.v b/spi_slave.v
index 435c59a..4628a9f 100644
--- a/spi_slave.v
+++ b/spi_slave.v
@@ -163,3 +163,4 @@ always @ (posedge clk) begin
 end
 
 endmodule
+`undefineall