diff --git a/src/clockinator.S b/src/clockinator.S
index 24e853c..2519057 100644
--- a/src/clockinator.S
+++ b/src/clockinator.S
@@ -21,6 +21,15 @@ isr_stop_blink:
     reti                                ; Exit interrupt
 
 main:
+    ; To compile on AtTiny25/45 comment out the SPH part
+    ; SPH is needed only on AtTiny85 which has >256b of SRAM
+    ldi         r16,         lo8(RAMEND)
+    out         SPL,        r0          ; Setup stack pointer LOW
+    ldi         r16,         hi8(RAMEND)
+    out         SPH,        r0          ; Setup stack pointer HIGH
+
+    sei                                 ; Global interrupt flag
+
     ;cbi        DDRB,       PB1         ; Set EC11 clockwise on PB5 as input
     ;cbi        DDRB,       PB2         ; Set EC11 counter-clockwise on PB3 as input
     ;cbi        DDRB,       PB5         ; Set EC11 button (555 square wave) on PB4 as input