diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index d77fdf356e98..710058eb2540 100644
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -178,7 +178,7 @@ static int read_from_imc_dir(char *imc_dir, int count)
 
 		return -1;
 	}
-	if (fscanf(fp, "%s", cas_count_cfg) <= 0) {
+	if (fscanf(fp, "%1023s", cas_count_cfg) <= 0) {
 		ksft_perror("Could not get iMC cas count read");
 		fclose(fp);
 
@@ -196,7 +196,7 @@ static int read_from_imc_dir(char *imc_dir, int count)
 
 		return -1;
 	}
-	if  (fscanf(fp, "%s", cas_count_cfg) <= 0) {
+	if  (fscanf(fp, "%1023s", cas_count_cfg) <= 0) {
 		ksft_perror("Could not get iMC cas count write");
 		fclose(fp);
 
diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
index 71ad2b335b83..fe3241799841 100644
--- a/tools/testing/selftests/resctrl/resctrlfs.c
+++ b/tools/testing/selftests/resctrl/resctrlfs.c
@@ -160,7 +160,7 @@ int get_cache_size(int cpu_no, char *cache_type, unsigned long *cache_size)
 
 		return -1;
 	}
-	if (fscanf(fp, "%s", cache_str) <= 0) {
+	if (fscanf(fp, "%63s", cache_str) <= 0) {
 		ksft_perror("Could not get cache_size");
 		fclose(fp);