diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index cc3ae2c290..afda71f39e 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1854,7 +1854,6 @@ virStorageFileGetSCSIKey;
 virStorageFileIsClusterFS;
 virStorageFileParseChainIndex;
 virStorageFileProbeFormat;
-virStorageFileProbeFormatFromBuf;
 virStorageFileResize;
 virStorageIsFile;
 virStorageNetHostDefClear;
diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
index 03b5a05cc2..de27890712 100644
--- a/src/storage/storage_backend_fs.c
+++ b/src/storage/storage_backend_fs.c
@@ -98,16 +98,8 @@ virStorageBackendProbeTarget(virStorageSourcePtr target,
             goto error;
         }
 
-        target->format = virStorageFileProbeFormatFromBuf(target->path,
-                                                          header, len);
-        if (target->format < 0) {
-            ret = -1;
-            goto error;
-        }
-
         if (!(meta = virStorageFileGetMetadataFromBuf(target->path,
                                                       header, len,
-                                                      target->format,
                                                       backingStore,
                                                       backingStoreFormat))) {
             ret = -1;
diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c
index 656e973543..2f0592f76e 100644
--- a/src/storage/storage_backend_gluster.c
+++ b/src/storage/storage_backend_gluster.c
@@ -293,12 +293,7 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state,
     if ((len = virStorageBackendGlusterReadHeader(fd, name, len, &header)) < 0)
         goto cleanup;
 
-    if ((vol->target.format = virStorageFileProbeFormatFromBuf(name,
-                                                               header,
-                                                               len)) < 0)
-        goto cleanup;
     if (!(meta = virStorageFileGetMetadataFromBuf(name, header, len,
-                                                  vol->target.format,
                                                   &vol->backingStore.path,
                                                   &vol->backingStore.format)))
         goto cleanup;
diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index 6870ae7c40..96af27bf00 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -713,7 +713,8 @@ virStorageIsFile(const char *backing)
     return true;
 }
 
-int
+
+static int
 virStorageFileProbeFormatFromBuf(const char *path,
                                  char *buf,
                                  size_t buflen)
@@ -971,16 +972,13 @@ virStorageFileMetadataNew(const char *path,
  * @path: name of file, for error messages
  * @buf: header bytes from @path
  * @len: length of @buf
- * @format: expected image format
  * @backing: output malloc'd name of backing image, if any
  * @backingFormat: format of @backing
  *
- * Extract metadata about the storage volume with the specified
- * image format. If image format is VIR_STORAGE_FILE_AUTO, it
- * will probe to automatically identify the format.  Does not recurse.
- *
- * Callers are advised never to use VIR_STORAGE_FILE_AUTO as a
- * format, since a malicious guest can turn a raw file into any
+ * Extract metadata about the storage volume, including probing its
+ * format.  Does not recurse.  Callers are advised not to trust the
+ * learned format if a guest has ever used the volume when it was
+ * raw, since a malicious guest can turn a raw file into any
  * other non-raw format at will.
  *
  * If the returned @backingFormat is VIR_STORAGE_FILE_AUTO
@@ -994,14 +992,13 @@ virStorageSourcePtr
 virStorageFileGetMetadataFromBuf(const char *path,
                                  char *buf,
                                  size_t len,
-                                 int format,
                                  char **backing,
                                  int *backingFormat)
 {
     virStorageSourcePtr ret = NULL;
     virStorageSourcePtr meta = NULL;
 
-    if (!(meta = virStorageFileMetadataNew(path, format)))
+    if (!(meta = virStorageFileMetadataNew(path, VIR_STORAGE_FILE_AUTO)))
         return NULL;
 
     if (virStorageFileGetMetadataInternal(meta, buf, len,
diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h
index 9e6cdbaf5c..33585ab731 100644
--- a/src/util/virstoragefile.h
+++ b/src/util/virstoragefile.h
@@ -260,8 +260,6 @@ struct _virStorageSource {
 # endif
 
 int virStorageFileProbeFormat(const char *path, uid_t uid, gid_t gid);
-int virStorageFileProbeFormatFromBuf(const char *path, char *buf,
-                                     size_t buflen);
 
 int virStorageFileGetMetadata(virStorageSourcePtr src,
                               uid_t uid, gid_t gid,
@@ -273,11 +271,10 @@ virStorageSourcePtr virStorageFileGetMetadataFromFD(const char *path,
 virStorageSourcePtr virStorageFileGetMetadataFromBuf(const char *path,
                                                      char *buf,
                                                      size_t len,
-                                                     int format,
                                                      char **backing,
                                                      int *backingFormat)
-    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(5)
-    ATTRIBUTE_NONNULL(6);
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(4)
+    ATTRIBUTE_NONNULL(5);
 int virStorageFileChainGetBroken(virStorageSourcePtr chain,
                                  char **broken_file);