diff --git a/fastboot/engine.c b/fastboot/engine.c
index e40db2b..345577d 100644
--- a/fastboot/engine.c
+++ b/fastboot/engine.c
@@ -187,6 +187,8 @@
     struct stat st;
 
     fd = fileno(tmpfile());
+    /* reset ext4fs info so we can be called multiple times */
+    reset_ext4fs_info();
     info.len = image->partition_size;
     make_ext4fs_internal(fd, NULL, NULL, 0, 0, 1, 0, 0, 0);
 
@@ -202,7 +204,7 @@
     close(fd);
 }
 
-int fb_format(Action *a, usb_handle *usb)
+int fb_format(Action *a, usb_handle *usb, int skip_if_not_supported)
 {
     const char *partition = a->cmd;
     char query[256];
@@ -218,6 +220,13 @@
     snprintf(query, sizeof(query), "getvar:partition-type:%s", partition);
     status = fb_command_response(usb, query, response);
     if (status) {
+        if (skip_if_not_supported) {
+            fprintf(stderr,
+                    "Erase successful, but not automatically formatting.\n");
+            fprintf(stderr,
+                    "Can't determine partition type.\n");
+            return 0;
+        }
         fprintf(stderr,"FAILED (%s)\n", fb_get_error());
         return status;
     }
@@ -229,6 +238,13 @@
         }
     }
     if (!generator) {
+        if (skip_if_not_supported) {
+            fprintf(stderr,
+                    "Erase successful, but not automatically formatting.\n");
+            fprintf(stderr,
+                    "File system type %s not supported.\n", response);
+            return 0;
+        }
         fprintf(stderr,"Formatting is not supported for filesystem with type '%s'.\n",
                 response);
         return -1;
@@ -238,6 +254,12 @@
     snprintf(query, sizeof(query), "getvar:partition-size:%s", partition);
     status = fb_command_response(usb, query, response);
     if (status) {
+        if (skip_if_not_supported) {
+            fprintf(stderr,
+                    "Erase successful, but not automatically formatting.\n");
+            fprintf(stderr, "Unable to get partition size\n.");
+            return 0;
+        }
         fprintf(stderr,"FAILED (%s)\n", fb_get_error());
         return status;
     }
@@ -266,11 +288,12 @@
     return status;
 }
 
-void fb_queue_format(const char *partition)
+void fb_queue_format(const char *partition, int skip_if_not_supported)
 {
     Action *a;
 
     a = queue_action(OP_FORMAT, partition);
+    a->data = (void*)skip_if_not_supported;
     a->msg = mkmsg("formatting '%s' partition", partition);
 }
 
@@ -482,7 +505,7 @@
         } else if (a->op == OP_NOTICE) {
             fprintf(stderr,"%s\n",(char*)a->data);
         } else if (a->op == OP_FORMAT) {
-            status = fb_format(a, usb);
+            status = fb_format(a, usb, (int)a->data);
             status = a->func(a, status, status ? fb_get_error() : "");
             if (status) break;
         } else {
diff --git a/fastboot/fastboot.c b/fastboot/fastboot.c
index fad70d4..805014f 100644
--- a/fastboot/fastboot.c
+++ b/fastboot/fastboot.c
@@ -636,7 +636,7 @@
             skip(2);
         } else if(!strcmp(*argv, "format")) {
             require(2);
-            fb_queue_format(argv[1]);
+            fb_queue_format(argv[1], 0);
             skip(2);
         } else if(!strcmp(*argv, "signature")) {
             require(2);
@@ -723,7 +723,9 @@
 
     if (wants_wipe) {
         fb_queue_erase("userdata");
+        fb_queue_format("userdata", 1);
         fb_queue_erase("cache");
+        fb_queue_format("cache", 1);
     }
     if (wants_reboot) {
         fb_queue_reboot();
diff --git a/fastboot/fastboot.h b/fastboot/fastboot.h
index c2f97a2..b77cb19 100644
--- a/fastboot/fastboot.h
+++ b/fastboot/fastboot.h
@@ -43,7 +43,7 @@
 /* engine.c - high level command queue engine */
 void fb_queue_flash(const char *ptn, void *data, unsigned sz);;
 void fb_queue_erase(const char *ptn);
-void fb_queue_format(const char *ptn);
+void fb_queue_format(const char *ptn, int skip_if_not_supported);
 void fb_queue_require(const char *prod, const char *var, int invert,
         unsigned nvalues, const char **value);
 void fb_queue_display(const char *var, const char *prettyname);