diff --git a/tasks/utilities/task_kmc.wdl b/tasks/utilities/task_kmc.wdl
index a8f32be4e..4d62c85a6 100644
--- a/tasks/utilities/task_kmc.wdl
+++ b/tasks/utilities/task_kmc.wdl
@@ -44,7 +44,7 @@ task kmc {
     tail -n8 LOG > ~{samplename}_kmer_stats.txt
   >>>
   output {
-    String est_genome_size = read_string("UNIQUE_COUNTED") 
+    Int est_genome_size = read_int("UNIQUE_COUNTED") 
     File kmer_stats = "~{samplename}_kmer_stats.txt"
     String kmc_version = read_string("VERSION")
   }
diff --git a/workflows/theiaprok/wf_theiaprok_ont.wdl b/workflows/theiaprok/wf_theiaprok_ont.wdl
index 06628be0a..6057ddce0 100644
--- a/workflows/theiaprok/wf_theiaprok_ont.wdl
+++ b/workflows/theiaprok/wf_theiaprok_ont.wdl
@@ -489,7 +489,7 @@ workflow theiaprok_ont {
     String? nanoplot_version = nanoplot_raw.nanoplot_version
     String? nanoplot_docker = nanoplot_raw.nanoplot_docker
     # Read QC - kmc outputs
-    String? kmc_est_genome_size = read_qc_trim.est_genome_size
+    Int? kmc_est_genome_size = read_qc_trim.est_genome_size
     File? kmc_kmer_stats = read_qc_trim.kmc_kmer_stats
     String? kmc_version = read_qc_trim.kmc_version
     # Read QC - rasusa outputs
diff --git a/workflows/utilities/wf_read_QC_trim_ont.wdl b/workflows/utilities/wf_read_QC_trim_ont.wdl
index 779d479c0..c0f361c84 100644
--- a/workflows/utilities/wf_read_QC_trim_ont.wdl
+++ b/workflows/utilities/wf_read_QC_trim_ont.wdl
@@ -84,7 +84,7 @@ workflow read_QC_trim_ont {
   }
   output { 
     # kmc outputs
-    String est_genome_size = kmc.est_genome_size
+    Int est_genome_size = kmc.est_genome_size
     File kmc_kmer_stats = kmc.kmer_stats
     String kmc_version = kmc.kmc_version