diff --git a/CHANGELOG.md b/CHANGELOG.md
index 723b276..105281d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,9 @@ Contact: campanam@si.edu
 [Deprecated](#deprecated)  
 
 ## aln2baits  
+### Version 1.8.0  
+Added --maxvars option to make variant haplotype definition more efficient/function properly  
+
 ### Version 1.7.8  
 Fixed bug in --shuffle option that caused infinite loop  
 Fixed hanging bug when running variant options  
@@ -142,6 +145,9 @@ Version constant added to header
 Preliminary script to generate baits from an annotation file and a reference sequence  
 
 ## baitslib  
+### Version 1.8.0  
+Handling for --maxvars option  
+
 ### Version 1.7.4  
 mean method uses .sum rather than .reduce(:+)  
 
@@ -295,6 +301,9 @@ New method write_probes handles basic output
 filter_probes definition removed into separate script for access by other scripts  
 
 ## baitstools  
+### Version 1.8.0  
+Handling for --maxvars option  
+
 ### Version 1.7.4  
 Conversion to a RubyGem  
 
@@ -459,6 +468,9 @@ The word 'probe' changed to 'baits' in all instances for clarity
 Set default for tiling offset as 20 bp (from 60 for select_snps and 25 for tile_probes)  
 
 ## baitstoolsgui  
+### Version 1.8.0  
+Handling for --maxvars option  
+
 ### Version 1.7.5  
 Fixed bug calling baitstools.rb rather than updated baitstools executable  
 
@@ -655,6 +667,9 @@ Version constant added to header
 Preliminary script to filter predefined baits through quality filters  
 
 ## osx_install  
+### Version 1.8.0  
+Installs latest baitstools gem (1.8.0)  
+
 ### Version 1.7.8  
 Installs latest baitstools gem (1.7.8)  
 
diff --git a/README.md b/README.md
index 0100eb7..4269207 100644
--- a/README.md
+++ b/README.md
@@ -43,14 +43,18 @@ The software is made available under the Smithsonian Institution [terms of use](
 General instructions for installation using RubyGems/Bundler and specific instructions for macOS are provided below. You can test your BaitsTools installation by running the tutorials included in the example_data directory. The archive "tutorial.tgz" includes the expected output of each tutorial. Note that vcf2baits and stacks2baits output will vary slightly due to the random number generator.  
 
 ### Installation using RubyGems and Bundler  
-The BaitsTools executables can be installed using [RubyGems](https://www.rubygems.org) and [Bundler](https://bundler.io/) (available on most UNIX-like operating systems with [Ruby](https://www.ruby-lang.org) and RubyGems installed). See instructions for macOS below as macOS requires the [Ruby Version Manager](https://rvm.io) to manually install Ruby gems. See the Ruby and RubyGems documentation for installation on other operating systems.  
+The BaitsTools executables can be installed using [RubyGems](https://www.rubygems.org) and [Bundler](https://bundler.io/) (available on most UNIX-like operating systems with [Ruby](https://www.ruby-lang.org) and RubyGems installed). See instructions for macOS below as macOS requires the [Ruby Version Manager](https://rvm.io) to manually install Ruby gems. See the Ruby and RubyGems documentation for installation on other operating systems. Precompiled gems are available [here](https://github.com/campanam/BaitsTools/pkgs/rubygems/baitstools).  
 
-In a terminal window, execute the following commands:  
+After downloading the latest precompiled gem, execute the following command in a terminal window:  
+
+`gem install baitstools-1.8.0.gem`  
+
+To manually build and install the gem, execute the following commands in a terminal window:  
 
 `git clone https://github.com/campanam/baitstools`  
 `cd baitstools`  
 `gem build baitstools.gemspec`  
-`gem install baitstools-1.7.8.gem`  
+`gem install baitstools-1.8.0.gem`  
 
 ### macOS Installation  
 macOS uses a deprecated version of Tcl-Tk as its default Tk framework. For best results, install [ActiveTcl 8.6](https://www.activestate.com/products/activetcl/downloads/) and then reinstall the tk gem (`gem install tk`). Tcl-Tk can also be installed using [Homebrew](https://brew.sh) or [Anaconda](https://anaconda.org/), but the windows are not optimized for these methods.  
@@ -74,7 +78,7 @@ Enter the following commands (step annotations are provided after the highlighte
 `git clone https://github.com/campanam/baitstools`: Download the BaitsTools repository.  
 `cd baitstools`: Enter the baitstools directory.  
 `gem build baitstools.gemspec`: Build the BaitsTools gem.  
-`gem install baitstools-1.7.5.gem`: Install the BaitsTools gem.  
+`gem install baitstools-1.8.0.gem`: Install the BaitsTools gem.  
 
 _macOS Installation Notes:_
 1. The Ruby Version Manager uses [Homebrew](https://brew.sh). During installation you may need to give an administrator password and authorization to install/update Homebrew.  
@@ -183,7 +187,8 @@ aln2baits generates baits from a DNA alignment in FASTA or FASTQ format. Bait se
 `-i, --input [FILE]`: Input alignment file name. Include the path to the file if not in the current directory.  
 `-L, --length [VALUE]`: Requested bait length. Default is 120 bp.  
 `-O, --offset [VALUE]`: Offset (in bp) between tiled baits. Default is 60 bp.  
-`-H, --haplo [VALUE]`: Alignment window haplotype definition (`haplotype` or `variant`). `haplotype` will cause the program to identify all unique haplotypes within each bait tiling window observed in the data. `variant` will cause the program to generate all possible permutations of single nucleotide variants observed within the window. Default is `haplotype`.  
+`-H, --haplo [VALUE]`: Alignment window haplotype definition (`haplotype` or `variant`). `haplotype` will cause the program to identify all unique haplotypes within each bait tiling window observed in the data. `variant` will cause the program to generate random permutations of single nucleotide variants observed within the window. Default is `haplotype`.  
+`--maxvars [VALUE]`: Maximum number of variant permutations to retain within each alignment window when using the `variant` haplotype definition. Default is 24.  
 
 ### annot2baits  
 annot2baits generates baits from an annotation file in GTF or GFF and a corresponding DNA sequence in FASTA or FASTQ format.  
@@ -232,7 +237,8 @@ pyrad2baits selects variants and generates baits from a PyRAD/ipyrad loci file.
 `-O, --offset [VALUE]`: Base pair offset between tiled baits. Default is 60 bp.  
 `-I, --minind [VALUE]`: Minimum number of individuals to include locus. Default is 1.  
 `-W, --strategy [VALUE]`: Strategy to generate baits from loci (`alignment`, `SNPs`, or `informative`). `alignment` treats the individual loci as FASTA alignments and passes the alignments to [aln2baits](#aln2baits) to generate weighted alignments. `SNPs` and `informative` select and generate baits for identified variable sites. `SNPs` includes all identified sites, whereas `informative` includes only phylogenetically informative sites. Default is `alignment`.  
-`-H, --haplo [VALUE]`: If using `alignment` strategy, alignment window haplotype definition (`haplotype` or `variant`). `haplotype` will cause the program to identify all unique haplotypes within each bait tiling window observed in the data. `variant` will cause the program to generate all possible permutations of single nucleotide variants observed within the window. Default is `haplotype`.  
+`-H, --haplo [VALUE]`: If using `alignment` strategy, alignment window haplotype definition (`haplotype` or `variant`). `haplotype` will cause the program to identify all unique haplotypes within each bait tiling window observed in the data. `variant` will cause the program to generate random permutations of single nucleotide variants observed within the window. Default is `haplotype`.  
+`--maxvars [VALUE]`: Maximum number of variant permutations to retain within each alignment window when using the `variant` haplotype definition. Default is 24.  
 `--uncollapsedref`: If using `SNPs` or `informative` strategies, choose a random reference sequence and keep ambiguities for each locus.  
 `-a, --alt`: If using `SNPs` or `informative` strategies, generate baits for alternate alleles.  
 `-t, --totalvars [VALUE]`: If using `SNPs` or `informative` strategies, total requested variants. Default is 30,000.  
diff --git a/baitstools.gemspec b/baitstools.gemspec
index 8eb6c95..eac777d 100644
--- a/baitstools.gemspec
+++ b/baitstools.gemspec
@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
 	s.name = 'baitstools'
-	s.version = '1.7.8'
+	s.version = '1.8.0'
 	s.required_ruby_version = '>= 2.4.1'
 	s.date = '2023-07-31'
 	s.summary = 'BaitsTools: Software for hybridization capture bait design'
diff --git a/bin/baitstools b/bin/baitstools
index c000697..3909d97 100644
--- a/bin/baitstools
+++ b/bin/baitstools
@@ -1,7 +1,7 @@
 #!/usr/bin/env ruby
 #-----------------------------------------------------------------------------------------------
 # baitstools
-BAITSTOOLSVER = "1.7.8"
+BAITSTOOLSVER = "1.8.0"
 # Michael G. Campana, 2017-2023
 # Smithsonian's National Zoo and Conservation Biology Institute
 #-----------------------------------------------------------------------------------------------
@@ -74,6 +74,7 @@ class Parser
 		args.no_Ns = false # Flag to omit bait sequences with Ns
 		args.collapse_ambiguities = false # Flag to collapse ambiguities to a single nucleotide
 		args.haplodef = "haplotype" # Haplotype definition for aln2baits
+		args.maxvars = 24 # Maximum number of retained variant permutations per window for aln2baits
 		args.uncollapsed_ref = false # Flag to keep ambiguities in pyrad reference sequence
 		args.sort = false # Flag to sort stack2baits SNPs by between/within population variation
 		args.hwe = false # Flag to sort stacks2baits SNPs by Hardy-Weinberg Equilibrium
@@ -186,6 +187,9 @@ class Parser
 					opts.on("-H","--haplo [VALUE]", String, "If using alignment strategy, window haplotype definition (haplotype or variant) (Default = haplotype)") do |fa|
 						args.haplodef = fa.downcase if fa != nil
 					end
+					opts.on("--maxvars [VALUE]",Integer, "Maximum number of variant permutations per alignment window (Default = 24)") do |maxvars|
+							args.maxvars = maxvars if maxvars != nil
+						end	
 					opts.on("--uncollapsedref","Keep ambiguities in pyrad2baits reference sequence") do
 						args.uncollapsed_ref = true
 					end
@@ -252,6 +256,9 @@ class Parser
 						opts.on("-H","--haplo [VALUE]", String, "Window haplotype definition (haplotype or variant) (Default = haplotype)") do |fa|
 							args.haplodef = fa if fa.downcase != nil
 						end
+						opts.on("--maxvars [VALUE]",Integer, "Maximum number of variant permutations per alignment window (Default = 24)") do |maxvars|
+							args.maxvars = maxvars if maxvars != nil
+						end	
 					end
 					if args.algorithm == "blast2baits"
 						opts.on("--percid [VALUE]", Float, "Minimum percent identity to include BLAST hit (Default = 0.0)") do |percid|
@@ -837,6 +844,14 @@ begin
 				print "Please choose a haplotype definition (haplotype or variant)\n"
 				$options.haplodef = gets.chomp.downcase
 			end
+			if $options.interact and $options.haplodef == "variant"
+				print "Enter maximum number of variant permutations per alignment window to retain.\n"
+				$options.maxvars = gets.chomp.to_i
+			end
+			while $options.maxvars <= 0 and $options.haplodef == "variant"
+				print "Minimum number of retained variant permutations must be greater than 0. Re-enter.\n"
+				$options.maxvars = gets.chomp.to_i
+			end
 		end
 		if $options.algorithm == "blast2baits"
 			if $options.interact
diff --git a/bin/baitstoolsgui b/bin/baitstoolsgui
index aaa9f7f..915a04d 100644
--- a/bin/baitstoolsgui
+++ b/bin/baitstoolsgui
@@ -1,7 +1,7 @@
 #!/usr/bin/env ruby
 #-----------------------------------------------------------------------------------------------
 # baitstoolsgui
-BAITSTOOLSGUI = "1.7.8"
+BAITSTOOLSGUI = "1.8.0"
 # Michael G. Campana, 2017-2023
 # Smithsonian's National Zoo and Conservation Biology Institute
 #-----------------------------------------------------------------------------------------------
@@ -58,6 +58,7 @@ def start_baitstools
 		end
 		if $options.algorithm == "aln2baits" or ($options.algorithm == "pyrad2baits" && $options.strategy == "alignment")
 			cmdline << " -H " + $options.haplodef
+			cmdline << " --maxvars " + $options.maxvars if $options.haplodef == "variant"
 		elsif $options.algorithm == "annot2baits"
 			cmdline << " -U " + $options.features.value.upcase
 		elsif $options.algorithm == "blast2baits"
@@ -235,6 +236,11 @@ def update_strategy
 		$alts.state = "disabled"
 		$uncollapsedref.state = "disabled"
 		$haplo.state = $haploselect.state = "normal"
+		if $options.haplodef == "variant"
+			$maxvars.state = $maxvarsentry.state = "normal"
+		else
+			$maxvars.state = $maxvarsentry.state = "disabled"
+		end
 	else
 		$maxsnpentry.state = $maxsnps.state = "normal"
 		$distanceentry.state = $distance.state = "normal"
@@ -244,6 +250,7 @@ def update_strategy
 		$alts.state = "normal"
 		$uncollapsedref.state = "normal"
 		$haplo.state = $haploselect.state = "disabled"
+		$maxvars.state = $maxvarsentry.state = "disabled"
 	end
 end
 #-----------------------------------------------------------------------------------------------
@@ -421,7 +428,31 @@ def haplodef_window
 		height 2
 		place('x' => 240, 'y' => 260)
 	end
-	$widgets.push($haplo, $haploselect)
+	$haploselect.bind("<ComboboxSelected>") do
+		update_haplodef
+	end
+	$maxvars = TkLabel.new($root) do
+		text 'Maximum variants per window'
+		font TkFont.new('times 20')
+		place('x' => 400, 'y' => 250)
+		pady 10
+	end
+	$maxvarsentry = TkEntry.new($root) do
+		textvariable $options.maxvars
+		borderwidth 5
+		font TkFont.new('times 12')
+		place('x' => 660, 'y' => 260)
+		width 10
+	end
+	$widgets.push($haplo, $haploselect,$maxvars,$maxvarsentry)
+end
+#-----------------------------------------------------------------------------------------------
+def update_haplodef
+	if $options.haplodef == "variant"
+		$maxvars.state = $maxvarsentry.state = "normal"
+	else
+		$maxvars.state = $maxvarsentry.state = "disabled"
+	end
 end
 #-----------------------------------------------------------------------------------------------
 def reference_window(winy = 150)
@@ -828,6 +859,7 @@ def subcommand_window(subcommand)
 		offset_window
 		haplodef_window
 		inputlabel = "Input FASTA/FASTQ"
+		update_haplodef
 	when "annot2baits"
 		reference_window
 		pad_window
@@ -1301,6 +1333,8 @@ def go_forward
 			Tk::messageBox :message => 'Please specify an input file.'
 		elsif ($options.algorithm == "annot2baits" or $options.algorithm == "bed2baits" or $options.algorithm == "blast2baits") && $options.refseq == ""
 			Tk::messageBox :message => 'Please specify a reference sequence.'
+		elsif $options.algorithm == "aln2baits" && $options.strategy == "alignment" && $options.haplodef == "variant" && $options.maxvars < 1
+			Tk::messageBox :message => 'Maximum number of variant permutations per window must be greater than 0.'
 		elsif ($options.algorithm == "annot2baits" or $options.algorithm == "bed2baits" or $options.algorithm == "blast2baits") && $options.pad < 0
 			Tk::messageBox :message => 'Pad length cannot be less than 0.'
 		elsif $options.baitlength < 1
@@ -1325,6 +1359,8 @@ def go_forward
 			Tk::messageBox :message => 'Tiling offset must be greater than 0.'
 		elsif $options.minind < 1
 			Tk::messageBox :message => 'Minimum individuals must be greater than 0.'
+		elsif $options.strategy == "alignment" && $options.haplodef == "variant" && $options.maxvars < 1
+			Tk::messageBox :message => 'Maximum number of variant permutations per window must be greater than 0.'
 		elsif $options.strategy != "alignment"
 			if $options.totalsnps < 1
 				Tk::messageBox :message => 'The total number of variants must be greater than 0.'
@@ -1532,6 +1568,7 @@ def set_defaults
 	$options.tileoffset = TkVariable.new(60) # Offset between tiled baits
 	$options.bait_type = TkVariable.new("RNA-DNA") # Hybridization type
 	$options.haplodef = TkVariable.new("haplotype") # Haplotype definition for aln2baits
+	$options.maxvars = TkVariable.new(24) # Maximum number of variant permutations per alignment window
 	$options.list_format = TkVariable.new("BED") # Interval list file format
 	$options.features = TkVariable.new("") # Desired features in comma-separated list
 	$options.pad = TkVariable.new(0) # BP to pad ends of extracted regions
@@ -1635,7 +1672,7 @@ $next_btn = TkButton.new($root) do
 	place('x' => 660, 'y' => 520)
 end
 credit = TkLabel.new($root) do
-	text "Michael G. Campana, 2017-2022\nSmithsonian's National Zoo and Conservation Biology Institute"
+	text "Michael G. Campana, 2017-2023\nSmithsonian's National Zoo and Conservation Biology Institute"
 	borderwidth 5
 	font TkFont.new('times 12')
 	pack("side" => "bottom",  "padx"=> "50", "pady"=> "10")
diff --git a/lib/aln2baits.rb b/lib/aln2baits.rb
index a64d1f1..a5697ca 100644
--- a/lib/aln2baits.rb
+++ b/lib/aln2baits.rb
@@ -1,7 +1,7 @@
 #!/usr/bin/env ruby
 #-----------------------------------------------------------------------------------------------
 # aln2baits
-ALN2BAITSVER = "1.7.8"
+ALN2BAITSVER = "1.8.0"
 # Michael G. Campana, 2017-2023
 # Smithsonian Conservation Biology Institute
 #-----------------------------------------------------------------------------------------------
@@ -40,7 +40,9 @@ def var_permutations(aln) # Get possible variant permutations
 		varindex = 1 # Index for sequence
 		for var in variants
 			varindex *= var.size # Must be complete down here or interferes with multithreading
+			break if varindex > $options.maxvars # Control unnecessary extra processing if too many variants requested
 		end
+		varindex = $options.maxvars if varindex > $options.maxvars
 		revised_haplos = []
 		bedstarts = self.bedstarts[0] # Reset bedstart array and assume coordinates of first array member
 		self.bedstarts = []
@@ -54,7 +56,7 @@ def var_permutations(aln) # Get possible variant permutations
 				for Thread.current[:k] in 0...varindex
 					if Thread.current[:k] % $options.threads == j
 						for Thread.current[:i] in 0...self.haplotypes[0].length
-							Thread.current[:var] = Thread.current[:k] % variants[Thread.current[:i]].size
+							Thread.current[:var] = rand(variants[Thread.current[:i]].size)
 							revised_haplos[Thread.current[:k]] << variants[Thread.current[:i]][Thread.current[:var]] # Minimize lock time
 						end
 						if $options.gaps == "extend"
diff --git a/lib/baitslib.rb b/lib/baitslib.rb
index f5257ad..1d6b820 100644
--- a/lib/baitslib.rb
+++ b/lib/baitslib.rb
@@ -1,8 +1,8 @@
 #!/usr/bin/env ruby
 #-----------------------------------------------------------------------------------------------
 # baitslib
-BAITSLIBVER = "1.7.5"
-# Michael G. Campana, 2017-2022
+BAITSLIBVER = "1.8.0"
+# Michael G. Campana, 2017-2023
 # Smithsonian's National Zoo and Conservation Biology Institute
 #-----------------------------------------------------------------------------------------------
 
@@ -1010,6 +1010,7 @@ def get_command_line # Get command line for summary output
 		end
 		if $options.algorithm == "aln2baits" or ($options.algorithm == "pyrad2baits" && $options.strategy == "alignment")
 			cmdline << " -H " + $options.haplodef
+			cmdline << " --maxvars " + $options.maxvars.to_s if $options.haplodef == "variant"
 		elsif $options.algorithm == "annot2baits"
 			cmdline << " -U "
 			for feature in $options.features
diff --git a/osx_install.sh b/osx_install.sh
index 15576d0..1b873b8 100644
--- a/osx_install.sh
+++ b/osx_install.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 #-----------------------------------------------------------------------------------------------
-# osx_install v 1.7.8
+# osx_install v 1.8.0
 # Michael G. Campana, 2017-2023
 # Smithsonian's National Zoo and Conservation Biology Institute
 #-----------------------------------------------------------------------------------------------
@@ -10,4 +10,4 @@ source ~/.rvm/scripts/rvm
 rvm install 3.1.2
 rvm --default use 3.1.2
 gem build baitstools.gemspec
-gem install ./baitstools-1.7.8.gem
+gem install ./baitstools-1.8.0.gem