diff --git a/c64/kernal/interrupts/irq_handler.s b/c64/kernal/interrupts/irq_handler.s
index aec36752..0d7d6de9 100644
--- a/c64/kernal/interrupts/irq_handler.s
+++ b/c64/kernal/interrupts/irq_handler.s
@@ -15,6 +15,8 @@ irq_handler:
 	tya
 	pha
 
+	cld // clear decimal flag, to prevent possible problems
+
 	// Check if caused by BRK
 	tsx
 	lda $0104, x // get the pre-interrupt processor state
diff --git a/c64/kernal/interrupts/nmi_handler.s b/c64/kernal/interrupts/nmi_handler.s
index 77a7a948..6c1275a0 100644
--- a/c64/kernal/interrupts/nmi_handler.s
+++ b/c64/kernal/interrupts/nmi_handler.s
@@ -2,6 +2,7 @@
 nmi_handler:
 
 	sei // don't allow IRQ to interfere, see https://www.c64-wiki.com/wiki/Interrupt
+	cld // clear decimal flag, to prevent possible problems
 
 	// Call interrupt routine (only if initialised)
 	pha