diff --git a/modules/nf-core/bwa/index/main.nf b/modules/nf-core/bwa/index/main.nf
index 2e48b6caae3..1c0fe573399 100644
--- a/modules/nf-core/bwa/index/main.nf
+++ b/modules/nf-core/bwa/index/main.nf
@@ -1,6 +1,8 @@
 process BWA_INDEX {
     tag "$fasta"
-    label 'process_single'
+    // NOTE requires 5.37N memory where N is the size of the database
+    // source: https://bio-bwa.sourceforge.net/bwa.shtml#8
+    memory { 6.B * fasta.size() }
 
     conda "${moduleDir}/environment.yml"
     container "${ workflow.containerEngine == 'singularity' && !task.ext.singularity_pull_docker_container ?
diff --git a/modules/nf-core/bwamem2/index/main.nf b/modules/nf-core/bwamem2/index/main.nf
index b7688285d76..162c75195c0 100644
--- a/modules/nf-core/bwamem2/index/main.nf
+++ b/modules/nf-core/bwamem2/index/main.nf
@@ -1,6 +1,8 @@
 process BWAMEM2_INDEX {
     tag "$fasta"
-    label 'process_single'
+    // NOTE Requires 28N GB memory where N is the size of the reference sequence
+    // source: https://github.com/bwa-mem2/bwa-mem2/issues/9
+    memory { 28.B * fasta.size() }
 
     conda "${moduleDir}/environment.yml"
     container "${ workflow.containerEngine == 'singularity' && !task.ext.singularity_pull_docker_container ?