diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 247e8dc..f7b85b2 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -371,7 +371,7 @@
 /*
  * Walk the mount table and build a list of local file systems
  */
-static int build_fs_mount_list(FsMountList *mounts)
+static void build_fs_mount_list(FsMountList *mounts, Error **err)
 {
     struct mntent *ment;
     FsMount *mount;
@@ -380,8 +380,8 @@
 
     fp = setmntent(mtab, "r");
     if (!fp) {
-        g_warning("fsfreeze: unable to read mtab");
-        return -1;
+        error_setg(err, "failed to open mtab file: '%s'", mtab);
+        return;
     }
 
     while ((ment = getmntent(fp))) {
@@ -405,8 +405,6 @@
     }
 
     endmntent(fp);
-
-    return 0;
 }
 #endif
 
@@ -433,15 +431,17 @@
     int ret = 0, i = 0;
     FsMountList mounts;
     struct FsMount *mount;
+    Error *local_err = NULL;
     int fd;
     char err_msg[512];
 
     slog("guest-fsfreeze called");
 
     QTAILQ_INIT(&mounts);
-    ret = build_fs_mount_list(&mounts);
-    if (ret < 0) {
-        return ret;
+    build_fs_mount_list(&mounts, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
+        return -1;
     }
 
     /* cannot risk guest agent blocking itself on a write in this state */
@@ -498,12 +498,12 @@
     FsMountList mounts;
     FsMount *mount;
     int fd, i = 0, logged;
+    Error *local_err = NULL;
 
     QTAILQ_INIT(&mounts);
-    ret = build_fs_mount_list(&mounts);
-    if (ret) {
-        error_set(err, QERR_QGA_COMMAND_FAILED,
-                  "failed to enumerate filesystems");
+    build_fs_mount_list(&mounts, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
         return 0;
     }
 
@@ -568,6 +568,7 @@
     FsMountList mounts;
     struct FsMount *mount;
     int fd;
+    Error *local_err = NULL;
     char err_msg[512];
     struct fstrim_range r = {
         .start = 0,
@@ -578,8 +579,9 @@
     slog("guest-fstrim called");
 
     QTAILQ_INIT(&mounts);
-    ret = build_fs_mount_list(&mounts);
-    if (ret < 0) {
+    build_fs_mount_list(&mounts, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(err, local_err);
         return;
     }