diff --git a/src/nf_modules/ont-guppy/main.nf b/src/nf_modules/ont-guppy/main.nf
index d806d33fafd8563efd0ae7af144375e455363aeb..5c615eb418620709319790bff584c89d734b0dba 100644
--- a/src/nf_modules/ont-guppy/main.nf
+++ b/src/nf_modules/ont-guppy/main.nf
@@ -53,7 +53,7 @@ guppy_basecaller --compress_fastq \
    --gpu_runners_per_device ${params.gpu_runners_per_device} \
    --num_callers ${params.num_callers} \
    --chunks_per_runner ${params.chunks_per_runner} \
-   ${params.config_file}
+   -c ${params.config_file}
 """
 }