diff --git a/nibabel/openers.py b/nibabel/openers.py
index a658c65c0a..ed9568c694 100644
--- a/nibabel/openers.py
+++ b/nibabel/openers.py
@@ -35,6 +35,9 @@
     del igzip, version
 
 except ImportError:
+    # nibabel.openers.IndexedGzipFile is imported by nibabel.volumeutils
+    # to detect compressed file types, so we give a fallback value here.
+    IndexedGzipFile = gzip.GzipFile
     HAVE_INDEXED_GZIP = False
 
 
diff --git a/nibabel/volumeutils.py b/nibabel/volumeutils.py
index c3a82db418..5852084ecd 100644
--- a/nibabel/volumeutils.py
+++ b/nibabel/volumeutils.py
@@ -19,7 +19,7 @@
 import numpy as np
 
 from .casting import (shared_range, type_info, OK_FLOATS)
-from .openers import Opener, BZ2File
+from .openers import Opener, BZ2File, IndexedGzipFile
 from .deprecated import deprecate_with_version
 from .externals.oset import OrderedSet
 
@@ -38,7 +38,7 @@
 default_compresslevel = 1
 
 #: file-like classes known to hold compressed data
-COMPRESSED_FILE_LIKES = (gzip.GzipFile, BZ2File)
+COMPRESSED_FILE_LIKES = (gzip.GzipFile, BZ2File, IndexedGzipFile)
 
 
 class Recoder(object):