diff --git a/plugins/validate.c b/plugins/validate.c
new file mode 100644
index 000000000..628ed9202
--- /dev/null
+++ b/plugins/validate.c
@@ -0,0 +1,134 @@
+/* The MIT License
+
+   Copyright (c) 2015 Genome Research Ltd.
+
+   Author: Petr Danecek <pd3@sanger.ac.uk>
+   
+   Permission is hereby granted, free of charge, to any person obtaining a copy
+   of this software and associated documentation files (the "Software"), to deal
+   in the Software without restriction, including without limitation the rights
+   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+   copies of the Software, and to permit persons to whom the Software is
+   furnished to do so, subject to the following conditions:
+   
+   The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software.
+   
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+   THE SOFTWARE.
+
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <htslib/vcf.h>
+#include <inttypes.h>
+#include <getopt.h>
+#include "bcftools.h"
+
+typedef struct
+{
+    bcf_hdr_t *hdr;
+    int marr, nerr_max, nerr;
+    int32_t *arr;
+}
+args_t;
+
+static args_t args;
+
+const char *about(void)
+{
+    return "Catch some of the common errors in VCF files.\n";
+}
+
+const char *usage(void)
+{
+    return 
+        "About: Catch some of the common errors in VCF files\n"
+        "       - ranges of GT indices\n"
+        "Usage: bcftools +validate [General Options] -- [Plugin Options]\n"
+        "Options:\n"
+        "   run \"bcftools plugin\" for a list of common options\n"
+        "\n"
+        "Plugin options:\n"
+        "   -n, --nrecords <int>        Number of records to report before exiting [1]\n"
+        "\n"
+        "Example:\n"
+        "   bcftools +validate file.vcf -- -n 10\n"
+        "\n";
+}
+
+
+int init(int argc, char **argv, bcf_hdr_t *in, bcf_hdr_t *out)
+{
+    memset(&args,0,sizeof(args_t));
+    args.hdr  = in;
+    args.nerr_max = 1;
+
+    int c;
+    static struct option loptions[] =
+    {
+        {"nrecords",1,0,'n'},
+        {0,0,0,0}
+    };
+    while ((c = getopt_long(argc, argv, "?hn:",loptions,NULL)) >= 0)
+    {
+        switch (c) 
+        {
+            case 'n': args.nerr_max = atoi(optarg);  break;
+            case 'h':
+            case '?':
+            default: fprintf(stderr,"%s", usage()); exit(1); break;
+        }
+    }
+    return 1;
+}
+
+void check_genotypes(args_t *args, bcf1_t *rec)
+{
+    if ( !rec->n_sample ) return;
+
+    int ngts = bcf_get_genotypes(args->hdr, rec, &args->arr, &args->marr);
+    ngts /= rec->n_sample;
+    int i, j;
+    
+    for (i=0; i<rec->n_sample; i++)
+    {
+        int32_t *ptr = args->arr + i*ngts;
+        for (j=0; j<ngts; j++)
+        {
+            if ( ptr[j]==bcf_int32_vector_end ) break;
+            if ( bcf_gt_is_missing(ptr[j]) ) continue;
+            int idx = bcf_gt_allele(ptr[j]);
+            if ( idx < 0 || idx >= rec->n_allele )
+            {
+                args->nerr++;
+                fprintf(stderr,"%s:%d\tsample %s has incorrect allele index %d\n", bcf_seqname(args->hdr,rec),rec->pos+1,args->hdr->samples[i],idx);
+                break;
+            }
+        }
+    }
+}
+
+bcf1_t *process(bcf1_t *rec)
+{
+    check_genotypes(&args, rec);
+
+    if ( args.nerr >= args.nerr_max )
+        error("Exiting, at least %d error%s found\n", args.nerr,args.nerr==1?"":"s");
+
+    return NULL;
+}
+
+void destroy(void)
+{
+    if ( args.nerr )
+        error("Found %d error%s\n", args.nerr,args.nerr==1?"":"s");
+
+    free(args.arr);
+}