diff --git a/substrate/.gitlab-ci.yml b/substrate/.gitlab-ci.yml
index 51ee7bcb1e..c6f23cd45f 100644
--- a/substrate/.gitlab-ci.yml
+++ b/substrate/.gitlab-ci.yml
@@ -37,6 +37,17 @@ cache:
 
 #### stage:                        test
 
+test:runtime:
+  stage:                           test
+  # image:                         alpine/git:latest
+  cache:                           {}
+  tags:
+    - linux-docker
+  only:
+    - /^[0-9]+$/
+  script:
+    - ./scripts/gitlab/check_runtime.sh
+
 
 test:rust:stable:                  &test
   stage:                           test
@@ -57,6 +68,8 @@ test:rust:stable:                  &test
   tags:
     - linux-docker
   before_script:
+   - echo "build cache size:"
+   - du -hs ${CARGO_HOME} ./target
    - ./scripts/build.sh
   script:
     - time cargo test --all --release --verbose --locked
diff --git a/substrate/scripts/gitlab/check_runtime.sh b/substrate/scripts/gitlab/check_runtime.sh
new file mode 100755
index 0000000000..89484f385e
--- /dev/null
+++ b/substrate/scripts/gitlab/check_runtime.sh
@@ -0,0 +1,70 @@
+#!/bin/sh
+# 
+# 
+# check for any changes in the node/src/runtime, srml/ and core/sr_* trees. if 
+# there are any changes found, it should mark the PR breaksconsensus and 
+# "auto-fail" the PR in some way unless a) the runtime is rebuilt and b) there 
+# isn't a change in the runtime/src/lib.rs file that alters the version.
+
+set -e # fail on any error
+
+# give some context
+git log --graph --oneline --decorate=short -n 10
+
+
+RUNTIME="node/runtime/wasm/target/wasm32-unknown-unknown/release/node_runtime.compact.wasm"
+
+
+
+# check if the wasm sources changed
+if ! git diff --name-only origin/master...${CI_COMMIT_SHA} \
+	| grep -q -e '^node/src/runtime' -e '^srml/' -e '^core/sr-'
+then
+	cat <<-EOT
+	
+	no changes to the runtime source code detected
+
+	EOT
+	exit 0
+fi
+
+
+
+# check for spec_version updates
+add_spec_version="$(git diff origin/master...${CI_COMMIT_SHA} node/runtime/src/lib.rs \
+	| sed -n -r 's/^\+[[:space:]]+spec_version: +([0-9]+),$/\1/p')"
+sub_spec_version="$(git diff origin/master...${CI_COMMIT_SHA} node/runtime/src/lib.rs \
+	| sed -n -r 's/^\-[[:space:]]+spec_version: +([0-9]+),$/\1/p')"
+
+
+# see if the spec version and the binary blob changed
+if git diff --name-only origin/master...${CI_COMMIT_SHA} \
+	| grep -q "${RUNTIME}" && \
+	[ "${add_spec_version}" != "${sub_spec_version}" ]
+then
+	cat <<-EOT
+	
+	changes to the runtime sources and changes in the spec version and wasm 
+	binary blob.
+
+	spec_version: ${sub_spec_version} -> ${add_spec_version}
+
+	EOT
+	exit 0
+fi
+
+
+cat <<-EOT
+
+wasm source files changed but not the spec version and the runtime
+binary blob. This may break the api.
+
+EOT
+
+
+
+
+
+exit 1
+
+# vim: noexpandtab