diff --git a/configs/example/ruby_gpu_random_test.py b/configs/example/ruby_gpu_random_test.py
index 0763454b41..029a97d42c 100644
--- a/configs/example/ruby_gpu_random_test.py
+++ b/configs/example/ruby_gpu_random_test.py
@@ -79,7 +79,7 @@ parser.add_argument("--random-seed", type=int, default=0,
                     help="Random seed number. Default value (i.e., 0) means \
                         using runtime-specific value")
 parser.add_argument("--log-file", type=str, default="gpu-ruby-test.log")
-parser.add_argument("--num-dmas", type=int, default=0,
+parser.add_argument("--num-dmas", type=int, default=None,
                     help="The number of DMA engines to use in tester config.")
 
 args = parser.parse_args()
@@ -108,7 +108,7 @@ if (args.system_size == "small"):
     args.wf_size = 1
     args.wavefronts_per_cu = 1
     args.num_cpus = 1
-    args.num_dmas = 1
+    n_DMAs = 1
     args.cu_per_sqc = 1
     args.cu_per_scalar_cache = 1
     args.num_compute_units = 1
@@ -117,7 +117,7 @@ elif (args.system_size == "medium"):
     args.wf_size = 16
     args.wavefronts_per_cu = 4
     args.num_cpus = 4
-    args.num_dmas = 2
+    n_DMAs = 2
     args.cu_per_sqc = 4
     args.cu_per_scalar_cache = 4
     args.num_compute_units = 4
@@ -126,11 +126,19 @@ elif (args.system_size == "large"):
     args.wf_size = 32
     args.wavefronts_per_cu = 4
     args.num_cpus = 4
-    args.num_dmas = 4
+    n_DMAs = 4
     args.cu_per_sqc = 4
     args.cu_per_scalar_cache = 4
     args.num_compute_units = 8
 
+# Number of DMA engines
+if not(args.num_dmas is None):
+    n_DMAs = args.num_dmas
+    # currently the tester does not support requests returned as
+    # aliased, thus we need num_dmas to be 0 for it
+    if not(args.num_dmas == 0):
+        print("WARNING: num_dmas != 0 not supported with VIPER")
+
 #
 # Set address range - 2 options
 #   level 0: small
@@ -173,9 +181,6 @@ tester_deadlock_threshold = 1e9
 # For now we're testing only GPU protocol, so we force num_cpus to be 0
 args.num_cpus = 0
 
-# Number of DMA engines
-n_DMAs = args.num_dmas
-
 # Number of CUs
 n_CUs = args.num_compute_units