diff --git a/src/arm/raspberry_pi.c b/src/arm/raspberry_pi.c
index 743f9f7..75381c1 100644
--- a/src/arm/raspberry_pi.c
+++ b/src/arm/raspberry_pi.c
@@ -159,7 +159,7 @@ mmap_regs()
 {
     // Already mapped!
     if (clk_reg || gpio_reg || pwm_reg) {
-        return;
+        return 0;
     }
 
     clk_reg = mmap_reg_addr(peripheral_base + CLOCK_OFFSET);