diff --git a/beacon_chain/beacon_node.nim b/beacon_chain/beacon_node.nim
index 1b652449c..9e0afa84b 100644
--- a/beacon_chain/beacon_node.nim
+++ b/beacon_chain/beacon_node.nim
@@ -814,7 +814,6 @@ proc start(node: BeaconNode, headState: BeaconState) =
       int64(node.blockPool.finalizedHead.slot.toBeaconTime()) -
       int64(node.beaconClock.now()),
     stateSlot = shortLog(headState.slot),
-    SHARD_COUNT,
     SLOTS_PER_EPOCH,
     SECONDS_PER_SLOT,
     SPEC_VERSION,
diff --git a/beacon_chain/version.nim b/beacon_chain/version.nim
index 8a5103c30..42a901953 100644
--- a/beacon_chain/version.nim
+++ b/beacon_chain/version.nim
@@ -5,12 +5,12 @@ type
     rlpxBackend
 
 const
-  network_type {.strdefine.} = "libp2p_daemon"
+  NETWORK_TYPE {.strdefine.} = "libp2p_daemon"
 
-  networkBackend* = when network_type == "rlpx": rlpxBackend
-                    elif network_type == "libp2p": libp2pBackend
-                    elif network_type == "libp2p_daemon": libp2pDaemonBackend
-                    else: {.fatal: "The 'network_type' should be either 'libp2p', 'libp2p_daemon' or 'rlpx'" .}
+  networkBackend* = when NETWORK_TYPE == "rlpx": rlpxBackend
+                    elif NETWORK_TYPE == "libp2p": libp2pBackend
+                    elif NETWORK_TYPE == "libp2p_daemon": libp2pDaemonBackend
+                    else: {.fatal: "The 'NETWORK_TYPE' should be either 'libp2p', 'libp2p_daemon' or 'rlpx'" .}
 
 const
   copyrights* = "Copyright (c) 2019 Status Research & Development GmbH"
@@ -35,5 +35,5 @@ const
     $versionMajor & "." & $versionMinor & "." & $versionBuild
 
   fullVersionStr* =
-    versionAsStr & " (" & gitRevision & ", " & network_type & ")"
+    versionAsStr & " (" & gitRevision & ", " & NETWORK_TYPE & ")"
 
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 93aae721d..a56da257e 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -28,7 +28,7 @@ ARG NETWORK_TYPE
 
 RUN cd nim-beacon-chain \
  && set -a \
- && . scripts/${NETWORK}.env \
+ && . scripts/load-testnet-nim-flags.sh scripts/${NETWORK}.env \
  && ./env.sh nim \
       -o:/usr/bin/beacon_node \
       -d:release \
@@ -38,10 +38,7 @@ RUN cd nim-beacon-chain \
       --verbosity:0 \
       --hints:off \
       --warnings:off \
-      -d:"network_type=${NETWORK_TYPE}" \
-      -d:"SHARD_COUNT=${SHARD_COUNT}" \
-      -d:"SLOTS_PER_EPOCH=${SLOTS_PER_EPOCH}" \
-      -d:"SECONDS_PER_SLOT=${SECONDS_PER_SLOT}" \
+      ${TESTNET_NIM_FLAGS} \
       -d:"chronicles_log_level=DEBUG" \
       -d:"testnet_servers_image" \
       c beacon_chain/beacon_node.nim
diff --git a/scripts/load-testnet-nim-flags.sh b/scripts/load-testnet-nim-flags.sh
new file mode 100644
index 000000000..aef3e6bb8
--- /dev/null
+++ b/scripts/load-testnet-nim-flags.sh
@@ -0,0 +1,21 @@
+set -a
+source $1
+set +a
+
+TESTNET_NIM_FLAGS=""
+
+testnet_env () {
+  eval "TESTNET_FLAG_VALUE=\$$1"
+  if [[ ! -z "$TESTNET_FLAG_VALUE" ]]; then
+    TESTNET_NIM_FLAGS+=" -d:$1=$TESTNET_FLAG_VALUE"
+  fi
+}
+
+testnet_env CONST_PRESET
+testnet_env NETWORK_TYPE
+testnet_env SLOTS_PER_EPOCH
+testnet_env SLOTS_PER_EPOCH
+testnet_env MAX_COMMITTEES_PER_SLOT
+
+export TESTNET_NIM_FLAGS
+
diff --git a/scripts/reset_testnet.sh b/scripts/reset_testnet.sh
index 783df0ea8..7df5e455d 100755
--- a/scripts/reset_testnet.sh
+++ b/scripts/reset_testnet.sh
@@ -5,7 +5,7 @@ set -eu
 cd $(dirname "$0")
 
 NETWORK_NAME=$1
-source "$NETWORK_NAME.env"
+source load-testnet-nim-flags.sh $NETWORK_NAME.env
 
 cd ..
 
diff --git a/scripts/testnet0.env b/scripts/testnet0.env
index dc4ea8760..f031f87bc 100644
--- a/scripts/testnet0.env
+++ b/scripts/testnet0.env
@@ -1,8 +1,5 @@
 CONST_PRESET=minimal
 NETWORK_TYPE=libp2p_daemon
-SHARD_COUNT=8
-SLOTS_PER_EPOCH=8
-SECONDS_PER_SLOT=6
 QUICKSTART_VALIDATORS=8
 RANDOM_VALIDATORS=120
 BOOTSTRAP_PORT=9000
diff --git a/scripts/testnet1.env b/scripts/testnet1.env
index 1dd241944..70c619bca 100644
--- a/scripts/testnet1.env
+++ b/scripts/testnet1.env
@@ -1,8 +1,8 @@
 CONST_PRESET=minimal
 NETWORK_TYPE=libp2p_daemon
-SHARD_COUNT=16
 SLOTS_PER_EPOCH=16
 SECONDS_PER_SLOT=16
+MAX_COMMITTEES_PER_SLOT=8
 QUICKSTART_VALIDATORS=40
 RANDOM_VALIDATORS=960
 BOOTSTRAP_PORT=9100
diff --git a/tests/simulation/start.sh b/tests/simulation/start.sh
index 5e7e08bbf..6a16f50bb 100755
--- a/tests/simulation/start.sh
+++ b/tests/simulation/start.sh
@@ -16,7 +16,7 @@ cd "$GIT_ROOT"
 
 NIMFLAGS="-d:chronicles_log_level=DEBUG --hints:off --warnings:off --verbosity:0 --opt:speed --debuginfo"
 
-# Run with "SHARD_COUNT=4 ./start.sh" to change these
+# Run with "SLOTS_PER_EPOCH=8 ./start.sh" to change these
 DEFS=""
 
 DEFS+="-d:MAX_COMMITTEES_PER_SLOT=${MAX_COMMITTEES_PER_SLOT:-1} "      # Spec default: 64