diff --git a/configure.ac b/configure.ac
index aadceac22..fc7182827 100644
--- a/configure.ac
+++ b/configure.ac
@@ -676,11 +676,11 @@ fi
 AC_MSG_CHECKING([whether libbz2 library is available])
 AC_MSG_RESULT([${have_bz2}])
 
-if test "x$have_bzip2" = "xno" ; then
+if test "x$have_bz2" = "xno" ; then
   have_local_bz2=yes
 else
   have_local_bz2=no
-endif
+fi
 AM_CONDITIONAL(HAVE_LOCAL_BZ2, [test "x$have_local_bz2" = xyes])
 
 # Note that szip management is tricky.
@@ -1860,7 +1860,7 @@ AC_SUBST(HAS_SZLIB_WRITE, [$have_sz])
 AC_SUBST(HAS_ZSTD,[$have_zstd])
 
 # Always available
-std_filters="deflate bzip2"
+std_filters="deflate bz2"
 if test "x$enable_szlib" = xyes ; then
 std_filters="${std_filters} szip"
 fi
diff --git a/libnczarr/zfilter.c b/libnczarr/zfilter.c
index 2e3b9119c..8bc38a63c 100644
--- a/libnczarr/zfilter.c
+++ b/libnczarr/zfilter.c
@@ -1379,23 +1379,23 @@ NCZ_load_plugin(const char* path, struct NCZ_Plugin** plugp)
 
     /* See what we have */
     {
-	H5PL_get_plugin_type_proto gpt =  (H5PL_get_plugin_type_proto)ncpgetsymbol(lib,"H5PLget_plugin_type");
-	H5PL_get_plugin_info_proto gpi =  (H5PL_get_plugin_info_proto)ncpgetsymbol(lib,"H5PLget_plugin_info");
-	NCZ_get_codec_info_proto  npi =  (NCZ_get_codec_info_proto)ncpgetsymbol(lib,"NCZ_get_codec_info");
-	NCZ_codec_info_defaults_proto  cpd =  (NCZ_codec_info_defaults_proto)ncpgetsymbol(lib,"NCZ_codec_info_defaults");
+	const H5PL_get_plugin_type_proto gpt =  (H5PL_get_plugin_type_proto)ncpgetsymbol(lib,"H5PLget_plugin_type");
+	const H5PL_get_plugin_info_proto gpi =  (H5PL_get_plugin_info_proto)ncpgetsymbol(lib,"H5PLget_plugin_info");
+	const NCZ_get_codec_info_proto  npi =  (NCZ_get_codec_info_proto)ncpgetsymbol(lib,"NCZ_get_codec_info");
+	const NCZ_codec_info_defaults_proto  cpd =  (NCZ_codec_info_defaults_proto)ncpgetsymbol(lib,"NCZ_codec_info_defaults");
 
 	if(gpt == NULL && gpi == NULL && npi == NULL && cpd == NULL)
 	    {stat = NC_ENOFILTER; goto done;}
 
 	if(cpd != NULL) {
 	    /* Deal with defaults first */
-	    NCZ_codec_t** cp = NULL;
+	    const NCZ_codec_t** cp = NULL;
 	    nclistpush(default_libs,lib);
-	    cp = cpd();
+	    cp = (const NCZ_codec_t**)cpd();
 #ifdef DEBUGL
 	    fprintf(stderr,"@@@ %s: default codec library found: %p\n",path,cp);
 #endif
-	    for(cp=cpd();*cp;cp++) {
+	    for(;*cp;cp++) {
 		    struct CodecAPI* c0;
 #ifdef DEBUGL
 		    fprintf(stderr,"@@@ %s: %s = %u\n",path,(*cp)->codecid,(*cp)->hdf5id);
diff --git a/nc_test4/Makefile.am b/nc_test4/Makefile.am
index 4145e542a..b8548404e 100644
--- a/nc_test4/Makefile.am
+++ b/nc_test4/Makefile.am
@@ -111,6 +111,12 @@ ref_filter_order_create.txt ref_filter_order_read.txt			\
 ref_any.cdl tst_specific_filters.sh                                     \
 tst_virtual_datasets.c
 
+# The tst_filterinstall test can only be run after an install
+# occurred with --with-plugin-dir enabled. So there is no point
+#in running it via make check. It is kept here so it can be
+# manually invoked if desired
+EXTRA_DIST += tst_filterinstall.sh
+
 CLEANFILES = tst_mpi_parallel.bin cdm_sea_soundings.nc bm_chunking.nc	\
 tst_floats_1D.cdl floats_1D_3.nc floats_1D.cdl tst_*.nc tmp_*.txt       \
 tst_floats2_*.cdl tst_ints2_*.cdl tst_shorts2_*.cdl tst_elena_*.cdl	\