diff --git a/piranha/analysis/haplo_functions.py b/piranha/analysis/haplo_functions.py
index c27b05e..90bc535 100644
--- a/piranha/analysis/haplo_functions.py
+++ b/piranha/analysis/haplo_functions.py
@@ -11,7 +11,6 @@
 
 
 def parse_partition_file(partition_file):
-
     partitions = collections.defaultdict(set)
     with open(partition_file, "r") as f:
         part = ""
@@ -35,6 +34,11 @@ def collapse_close(flopp_file,distance_cutoff,vcf_file):
     final_haplos = []
     vcf = parse_VCF(vcf_file)
     parsed_flopp = parse_flopp_reads(flopp_file)
+    #if flopp wasn't run then the file is empty, parsing gives empty list
+    #need a single partition containing all reads
+    if parsed_flopp == []:
+        return [[0]]
+
     for h in parsed_flopp:
         collapse_into_current = [haplo_pos]
         if haplo_pos in collapsed:
@@ -176,7 +180,12 @@ def parse_support_col(col):
     total_reads = 0
     base_support = {}
     for base in base_split:
-        base_val,support_reads = base.split(':')
+        try:
+            base_val,support_reads = base.split(':')
+        except ValueError:
+            # -1 in the support col - means zero reads in partition overlap this position
+            base_val = '-1'
+            support_reads = 0
         # if base_val == selbase_val:
         #     base_support = int(support_reads)
         base_support[base_val] = int(support_reads)
@@ -187,6 +196,9 @@ def check_site_sig(base_support,allele_freqs):
     #check if allele freqs are consistent with random sample from overall reads for this site
     #need to know these are the same order
     #reads might have 100% one allele, need to insert zero in this case, then sort to make sure order correct
+    if '-1' in base_support.keys():
+        # zero read coverage, this site shouldn't be significant
+        return False
     for key in allele_freqs:
         if key not in base_support:
             base_support[key] = 0
@@ -226,7 +238,16 @@ def get_haplo_dist(h1,h2,parsed_VCF):
 def sum_base_support(dict1,dict2):
     out_dict = {}
     for key in dict1:
-        out_dict[key] = dict1[key] + dict2[key]
+        try:
+            out_dict[key] = dict1[key] + dict2[key]
+        except KeyError:
+            #base not recorded in dict2 - probably a -1 col
+            out_dict[key] = dict1[key]
+    # check for extra keys in other dict
+    for key in dict2:
+        if key not in dict1.keys():
+            out_dict[key] = dict2[key]
+
     return out_dict
 
 def calc_sd(haplotypes):
diff --git a/piranha/scripts/piranha_haplotype.smk b/piranha/scripts/piranha_haplotype.smk
index 3a9e79b..52890ce 100644
--- a/piranha/scripts/piranha_haplotype.smk
+++ b/piranha/scripts/piranha_haplotype.smk
@@ -85,8 +85,11 @@ rule flopp:
         partition = os.path.join(config[KEY_TEMPDIR],"reference_analysis","{reference}","haplotyping","flopp_partitions","{reference}_part.txt")
     shell:
         """
-        VARIANTS=$(grep -v '#' {input.vcf} | wc -l)
-        if [[ $VARIANTS -gt 0 ]]
+        # || true to stop snakemake catching the exit code 1 grep returns on finding zero lines
+        VARIANTS=$((grep -v '#' {input.vcf} | wc -l) || true)
+        echo "Number of variants"
+        echo $VARIANTS
+        if [[ $VARIANTS -gt 1 ]]
         then
             flopp -b {input.bam:q} \
             -c {input.vcf:q} \
@@ -95,7 +98,7 @@ rule flopp:
             -o {output.flopp:q} \
             -P {params.partition_path} 
         else
-            echo "No variants called - single reference haplotype"
+            echo "Less than 2 variants called - haplotyping not possible, one haplotype will be output"
             touch {output.partition:q}
             touch {output.flopp:q}
         fi
@@ -129,10 +132,14 @@ rule haplotype_qc:
         with open(output.txt,"w") as fhaplo:
             merged_haplo_count = 0
             for subset in merge_info:
-                reads = set()
-                for part in subset:
-                    part_reads = partitions[part]
-                    reads = reads.union(part_reads)
+                if subset == [0] and len(merge_info) == 1:
+                    # flopp wasn't run, single haplo to be called using all reads
+                    reads = [read for read in seq_index]
+                else:
+                    reads = set()
+                    for part in subset:
+                        part_reads = partitions[part]
+                        reads = reads.union(part_reads)
 
                 if len(reads) > params.min_reads:
                     print(green(f"Haplotype HAP0{merged_haplo_count}:"), len(reads), "reads")