diff --git a/include/linux/timecounter.h b/include/linux/timecounter.h
index 754b74a2167f..c6540ceea143 100644
--- a/include/linux/timecounter.h
+++ b/include/linux/timecounter.h
@@ -124,7 +124,7 @@ extern u64 timecounter_read(struct timecounter *tc);
  * This allows conversion of cycle counter values which were generated
  * in the past.
  */
-extern u64 timecounter_cyc2time(struct timecounter *tc,
+extern u64 timecounter_cyc2time(const struct timecounter *tc,
 				u64 cycle_tstamp);
 
 #endif
diff --git a/kernel/time/timecounter.c b/kernel/time/timecounter.c
index 85b98e727306..e6285288d765 100644
--- a/kernel/time/timecounter.c
+++ b/kernel/time/timecounter.c
@@ -76,7 +76,7 @@ static u64 cc_cyc2ns_backwards(const struct cyclecounter *cc,
 	return ns;
 }
 
-u64 timecounter_cyc2time(struct timecounter *tc,
+u64 timecounter_cyc2time(const struct timecounter *tc,
 			 u64 cycle_tstamp)
 {
 	u64 delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask;