diff --git a/fpga/rtl/puzzlefw_pkg.vhd b/fpga/rtl/puzzlefw_pkg.vhd
index a9b357f..d407e13 100644
--- a/fpga/rtl/puzzlefw_pkg.vhd
+++ b/fpga/rtl/puzzlefw_pkg.vhd
@@ -29,10 +29,10 @@ package puzzlefw_pkg is
     constant reg_rcnt:          natural := 16#000200#;
     constant reg_wcnt:          natural := 16#000204#;
     constant reg_start:         natural := 16#000208#;
+    constant reg_test_irq:      natural := 16#000400#;
+    constant reg_test_led:      natural := 16#000404#;
     constant reg_dma_buf_addr:  natural := 16#100000#;
     constant reg_dma_buf_size:  natural := 16#100004#;
-    constant reg_test_irq:      natural := 16#100100#;
-    constant reg_test_led:      natural := 16#100104#;
 
     -- Firmware info word.
     constant fw_api_version:    natural := 1;
diff --git a/fpga/rtl/puzzlefw_top.vhd b/fpga/rtl/puzzlefw_top.vhd
index 771992c..96811ab 100644
--- a/fpga/rtl/puzzlefw_top.vhd
+++ b/fpga/rtl/puzzlefw_top.vhd
@@ -153,7 +153,8 @@ architecture arch of puzzlefw_top is
 
 begin
 
-    s_irq <= s_reg_control.test_irq;
+    s_irq(7 downto 1) <= s_reg_control.test_irq(7 downto 1);
+    s_irq(0) <= s_reg_control.test_irq(0) and s_reg_control.irq_enable;
     led_o(7 downto 2) <= s_reg_control.test_led(7 downto 2);
 
     -- Differential clock input for ADC clock.