diff --git a/modules/nf-core/gatk4/germlinecnvcaller/main.nf b/modules/nf-core/gatk4/germlinecnvcaller/main.nf
index f42ceb6af73..4faff97f517 100644
--- a/modules/nf-core/gatk4/germlinecnvcaller/main.nf
+++ b/modules/nf-core/gatk4/germlinecnvcaller/main.nf
@@ -37,7 +37,7 @@ process GATK4_GERMLINECNVCALLER {
         avail_mem = (task.memory.mega*0.8).intValue()
     }
     """
-    gatk --java-options "-Xmx${avail_mem}g -XX:-UsePerfData" \\
+    gatk --java-options "-Xmx${avail_mem}M -XX:-UsePerfData" \\
         GermlineCNVCaller \\
         $input_list \\
         $ploidy_command \\
diff --git a/modules/nf-core/gatk4/postprocessgermlinecnvcalls/main.nf b/modules/nf-core/gatk4/postprocessgermlinecnvcalls/main.nf
index ef9a34a333e..978d15f915a 100644
--- a/modules/nf-core/gatk4/postprocessgermlinecnvcalls/main.nf
+++ b/modules/nf-core/gatk4/postprocessgermlinecnvcalls/main.nf
@@ -35,7 +35,7 @@ process GATK4_POSTPROCESSGERMLINECNVCALLS {
         avail_mem = (task.memory.mega*0.8).intValue()
     }
     """
-    gatk --java-options "-Xmx${avail_mem}g -XX:-UsePerfData" \\
+    gatk --java-options "-Xmx${avail_mem}M -XX:-UsePerfData" \\
         PostprocessGermlineCNVCalls \\
         $calls_command \\
         $model_command \\