diff --git a/updater/install.c b/updater/install.c
index db2bd32..ff7de47 100644
--- a/updater/install.c
+++ b/updater/install.c
@@ -151,13 +151,13 @@
         const MtdPartition* mtd;
         mtd = mtd_find_partition_by_name(location);
         if (mtd == NULL) {
-            printf("%s: no mtd partition named \"%s\"",
+            uiPrintf(state, "%s: no mtd partition named \"%s\"",
                     name, location);
             result = strdup("");
             goto done;
         }
         if (mtd_mount_partition(mtd, mount_point, fs_type, 0 /* rw */) != 0) {
-            printf("mtd mount of %s failed: %s\n",
+            uiPrintf(state, "mtd mount of %s failed: %s\n",
                     location, strerror(errno));
             result = strdup("");
             goto done;
@@ -167,7 +167,7 @@
         if (mount(location, mount_point, fs_type,
                   MS_NOATIME | MS_NODEV | MS_NODIRATIME,
                   has_mount_options ? mount_options : "") < 0) {
-            printf("%s: failed to mount %s at %s: %s\n",
+            uiPrintf(state, "%s: failed to mount %s at %s: %s\n",
                     name, location, mount_point, strerror(errno));
             result = strdup("");
         } else {
@@ -231,10 +231,14 @@
     scan_mounted_volumes();
     const MountedVolume* vol = find_mounted_volume_by_mount_point(mount_point);
     if (vol == NULL) {
-        printf("unmount of %s failed; no such volume\n", mount_point);
+        uiPrintf(state, "unmount of %s failed; no such volume\n", mount_point);
         result = strdup("");
     } else {
-        unmount_mounted_volume(vol);
+        int ret = unmount_mounted_volume(vol);
+        if (ret != 0) {
+           uiPrintf(state, "unmount of %s failed (%d): %s\n",
+                    mount_point, ret, strerror(errno));
+        }
         result = mount_point;
     }