diff --git a/ntedit.cpp b/ntedit.cpp
index acd4220..8cf53a1 100644
--- a/ntedit.cpp
+++ b/ntedit.cpp
@@ -559,7 +559,7 @@ str_to_upper(const std::string& str)
 
 /* Helper for filling out the LPS array for detecting a low complexity repeat. */
 void
-computeLPSArray(std::string possible_repeat, int n, std::vector<int>& lps)
+computeLPSArray(const std::string& possible_repeat, int n, std::vector<int>& lps)
 {
 	int len = 0;
 	int i;
@@ -810,7 +810,7 @@ makeDeletion(
 
 /* Returns the character at pos based on the seqNode structure. */
 unsigned char
-getCharacter(unsigned& pos, seqNode node, const std::string& contigSeq)
+getCharacter(unsigned& pos, const seqNode& node, const std::string& contigSeq)
 {
 	if (node.node_type == 0) {
 		return contigSeq.at(pos);
diff --git a/src/ntedit_make_genome_bf.cpp b/src/ntedit_make_genome_bf.cpp
index 73dcd4d..37adfc3 100644
--- a/src/ntedit_make_genome_bf.cpp
+++ b/src/ntedit_make_genome_bf.cpp
@@ -20,7 +20,7 @@ const unsigned NUM_BITS_PER_BYTE = 8;
 /*
 Return the genome size of the given fasta file
 */
-uint64_t find_genome_size(std::vector<std::string> genome_files, int threads) {
+uint64_t find_genome_size(const std::vector<std::string>& genome_files, int threads) {
   uint64_t genome_size = 0;
   for (const auto& genome_file : genome_files) {
     btllib::SeqReader reader(