diff --git a/dhrystone/stdlib.c b/dhrystone/stdlib.c
index 55150a7..f88023b 100644
--- a/dhrystone/stdlib.c
+++ b/dhrystone/stdlib.c
@@ -26,7 +26,7 @@ int heap_memory_used = 0;
 long time()
 {
 	int cycles;
-	asm("rdcycle %0" : "=r"(cycles));
+	asm volatile ("rdcycle %0" : "=r"(cycles));
 	// printf("[time() -> %d]", cycles);
 	return cycles;
 }
@@ -34,7 +34,7 @@ long time()
 long insn()
 {
 	int insns;
-	asm("rdinstret %0" : "=r"(insns));
+	asm volatile ("rdinstret %0" : "=r"(insns));
 	// printf("[insn() -> %d]", insns);
 	return insns;
 }
@@ -46,7 +46,7 @@ char *malloc(int size)
 	// printf("[malloc(%d) -> %d (%d..%d)]", size, (int)p, heap_memory_used, heap_memory_used + size);
 	heap_memory_used += size;
 	if (heap_memory_used > 1024)
-		asm("ebreak");
+		asm volatile ("ebreak");
 	return p;
 }
 
diff --git a/firmware/stats.c b/firmware/stats.c
index 4a06751..80e22dd 100644
--- a/firmware/stats.c
+++ b/firmware/stats.c
@@ -28,7 +28,7 @@ static void stats_print_dec(unsigned int val, int digits, bool zero_pad)
 void stats(void)
 {
 	unsigned int num_cycles, num_instr;
-	__asm__("rdcycle %0; rdinstret %1;" : "=r"(num_cycles), "=r"(num_instr));
+	__asm__ volatile ("rdcycle %0; rdinstret %1;" : "=r"(num_cycles), "=r"(num_instr));
 	print_str("Cycle counter ........");
 	stats_print_dec(num_cycles, 8, false);
 	print_str("\nInstruction counter ..");