diff --git a/tools/csr.c b/tools/csr.c
index 15ae7c4..9408fb6 100644
--- a/tools/csr.c
+++ b/tools/csr.c
@@ -567,7 +567,7 @@ char *csr_buildidtostr(uint16_t id)
 		if (csr_map[i].id == id)
 			return csr_map[i].str;
 
-	snprintf(str, 11, "Build %d", id);
+	snprintf(str, sizeof(str), "Build %d", id);
 	return str;
 }
 
diff --git a/tools/hciattach_st.c b/tools/hciattach_st.c
index 474545a..85a2e08 100644
--- a/tools/hciattach_st.c
+++ b/tools/hciattach_st.c
@@ -120,7 +120,7 @@ static int load_file(int dd, uint16_t version, const char *suffix)
 {
 	DIR *dir;
 	struct dirent *d;
-	char pathname[PATH_MAX], filename[NAME_MAX], prefix[20];
+	char pathname[PATH_MAX], filename[NAME_MAX + 2], prefix[20];
 	unsigned char cmd[256];
 	unsigned char buf[256];
 	uint8_t seqnum = 0;