diff --git a/lib/config/config.c b/lib/config/config.c
index 25a87c983..aedbb2b1e 100644
--- a/lib/config/config.c
+++ b/lib/config/config.c
@@ -522,7 +522,7 @@ int config_file_read_fd(struct dm_config_tree *cft, struct device *dev, dev_io_r
 	if (!(dev->flags & DEV_REGULAR) || size2)
 		use_plain_read = 0;
 
-	if (!(buf = malloc(size + size2))) {
+	if (!(buf = zalloc(size + size2))) {
 		log_error("Failed to allocate circular buffer.");
 		return 0;
 	}
diff --git a/tools/pvck.c b/tools/pvck.c
index 629e1feee..0d1bc1b17 100644
--- a/tools/pvck.c
+++ b/tools/pvck.c
@@ -2955,7 +2955,7 @@ static int _read_metadata_file(struct cmd_context *cmd, struct metadata_file *mf
 		goto out;
 	}
 
-	if (!(text_buf = zalloc(text_size + 1)))
+	if (!(text_buf = malloc(text_size + 1)))
 		goto_out;
 
 	rv = read(fd, text_buf, text_size);
@@ -2964,8 +2964,7 @@ static int _read_metadata_file(struct cmd_context *cmd, struct metadata_file *mf
 		free(text_buf);
 		goto out;
 	}
-
-	text_size += 1; /* null terminating byte */
+	text_buf[text_size++] = 0; /* null terminating byte */
 
 	if (close(fd))
 		stack;
diff --git a/tools/pvscan.c b/tools/pvscan.c
index ec33c9a9a..b19b74b3e 100644
--- a/tools/pvscan.c
+++ b/tools/pvscan.c
@@ -223,6 +223,7 @@ static int _online_pvid_file_read(char *path, int *major, int *minor, char *vgna
 		log_warn("No info in %s", path);
 		return 0;
 	}
+	buf[rv] = 0; /* \0 terminated buffer */
 
 	if (sscanf(buf, "%d:%d", major, minor) != 2) {
 		log_warn("No device numbers in %s", path);