diff --git a/arch/x86_64/kernel/perfctr.c b/arch/x86_64/kernel/perfctr.c
index f057a8ca..85741457 100644
--- a/arch/x86_64/kernel/perfctr.c
+++ b/arch/x86_64/kernel/perfctr.c
@@ -20,7 +20,7 @@
 
 extern unsigned int *x86_march_perfmap;
 extern int running_on_kvm(void);
-int ihk_mc_perfctr_fixed_init(int counter, int mode);
+static int ihk_mc_perfctr_fixed_init(int counter, int mode);
 
 //#define PERFCTR_DEBUG
 #ifdef PERFCTR_DEBUG
@@ -354,7 +354,7 @@ int ihk_mc_perfctr_stop(unsigned long counter_mask)
 }
 
 // init for fixed counter
-int ihk_mc_perfctr_fixed_init(int counter, int mode)
+static int ihk_mc_perfctr_fixed_init(int counter, int mode)
 {
 	unsigned long value = 0;
 	unsigned int  ctr_mask = 0xf;
diff --git a/lib/include/ihk/perfctr.h b/lib/include/ihk/perfctr.h
index 800acb6a..b9695623 100644
--- a/lib/include/ihk/perfctr.h
+++ b/lib/include/ihk/perfctr.h
@@ -65,7 +65,6 @@ int ihk_mc_perfctr_init_raw(int counter, unsigned int code, int mode);
 int ihk_mc_perfctr_set_extra(struct mc_perf_event *event);
 int ihk_mc_perfctr_start(unsigned long counter_mask);
 int ihk_mc_perfctr_stop(unsigned long counter_mask);
-int ihk_mc_perfctr_fixed_init(int counter, int mode);
 int ihk_mc_perfctr_reset(int counter);
 int ihk_mc_perfctr_set(int counter, long value);
 int ihk_mc_perfctr_read_mask(unsigned long counter_mask, unsigned long *value);