diff --git a/.gitattributes b/.gitattributes
index a31ec1348e660..854f73a7794f6 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -9,3 +9,5 @@
 *.zip binary
 *.png binary
 *.jpg binary
+*.tgz binary
+*.tar.gz binary
diff --git a/build.sh b/build.sh
index abfc6eef410d2..4b9c8d64747e3 100755
--- a/build.sh
+++ b/build.sh
@@ -2,7 +2,7 @@
 set -euo pipefail
 
 bail="--bail"
-run_tests="true"
+runtarget="build+test"
 while [[ "${1:-}" != "" ]]; do
     case $1 in
         -h|--help)
@@ -16,7 +16,7 @@ while [[ "${1:-}" != "" ]]; do
             export CDK_BUILD="--force"
             ;;
         --skip-test|--skip-tests)
-            run_tests="false"
+            runtarget="build"
             ;;
         *)
             echo "Unrecognized parameter: $1"
@@ -53,9 +53,8 @@ trap "rm -rf $MERKLE_BUILD_CACHE" EXIT
 
 echo "============================================================================================="
 echo "building..."
-time lerna run $bail --stream build+test || fail
+time lerna run $bail --stream $runtarget || fail
 
-#TEMPORARILY DISABLED (benisrae)
-#/bin/bash scripts/check-api-compatibility.sh
+/bin/bash scripts/check-api-compatibility.sh
 
 touch $BUILD_INDICATOR
diff --git a/package-lock.json b/package-lock.json
index cfedc4b7e6b16..3d33ee191ace3 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4035,9 +4035,9 @@
       }
     },
     "flatted": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/flatted/-/flatted-2.0.0.tgz",
-      "integrity": "sha512-R+H8IZclI8AAkSBRQJLVOsxwAoHd6WC40b4QTNWIjzAa6BXOBfQcM587MXDTVPeYaopFNWHUFLx7eNmHDSxMWg==",
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/flatted/-/flatted-2.0.1.tgz",
+      "integrity": "sha512-a1hQMktqW9Nmqr5aktAux3JMNqaucxGcjtjWnZLHX7yyPCmlSV3M54nGYbqT8K+0GhF3NBgmJCc3ma+WOgX8Jg==",
       "dev": true
     },
     "flush-write-stream": {
@@ -6526,9 +6526,8 @@
       "dev": true
     },
     "jsii-diff": {
-      "version": "0.12.1",
-      "resolved": "https://registry.npmjs.org/jsii-diff/-/jsii-diff-0.12.1.tgz",
-      "integrity": "sha512-naOCIY667EBSksuWUp8UBTr2fhA67r5dZgrjxZXLS+NuZu8lq4oNDaRcbmGHjZEAwedSrgHMhbu4eWSebn+XxQ==",
+      "version": "file:vendored_deps/jsii-diff-0.12.x.tgz",
+      "integrity": "sha512-XtebcjTMuSviRiaH+EoeYw6mfnWr+JiRyqWW/pELJXIgA1L4T6v3ENpSPxjKALcdivFuruKaFF8B6VVV7TXX9A==",
       "dev": true,
       "requires": {
         "jsii-reflect": "^0.12.1",
@@ -7069,15 +7068,15 @@
       "dev": true
     },
     "log4js": {
-      "version": "4.3.2",
-      "resolved": "https://registry.npmjs.org/log4js/-/log4js-4.3.2.tgz",
-      "integrity": "sha512-72GjgSP+ifL156MD/bXEhE7UlFLKS2KkCXujodb1nl1z6PpKhCfS+41dyNQ7zKi4iM49TQl+aWLEISXGLcGCCQ==",
+      "version": "4.4.0",
+      "resolved": "https://registry.npmjs.org/log4js/-/log4js-4.4.0.tgz",
+      "integrity": "sha512-xwRvmxFsq8Hb7YeS+XKfvCrsH114bXex6mIwJ2+KmYVi23pB3+hlzyGq1JPycSFTJWNLhD/7PCtM0RfPy6/2yg==",
       "dev": true,
       "requires": {
         "date-format": "^2.0.0",
         "debug": "^4.1.1",
         "flatted": "^2.0.0",
-        "rfdc": "^1.1.2",
+        "rfdc": "^1.1.4",
         "streamroller": "^1.0.5"
       },
       "dependencies": {
diff --git a/package.json b/package.json
index d3408b5e5b8f4..38ba28b14555d 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
     "@types/nodeunit": "^0.0.30",
     "conventional-changelog-cli": "^2.0.21",
     "jest": "^24.8.0",
-    "jsii-diff": "^0.12.1",
+    "jsii-diff": "file:vendored_deps/jsii-diff-0.12.x.tgz",
     "lerna": "^3.15.0",
     "nodeunit": "^0.11.3",
     "nyc": "^14.1.1",
diff --git a/scripts/check-api-compatibility.sh b/scripts/check-api-compatibility.sh
index 95c31461cd370..ad63043b13427 100755
--- a/scripts/check-api-compatibility.sh
+++ b/scripts/check-api-compatibility.sh
@@ -49,7 +49,7 @@ success=true
 for i in ${!package_dirs[*]}; do
     if [[ ! -d $tmpdir/node_modules/${package_names[$i]} ]]; then continue; fi
     echo -n "${package_names[$i]}... "
-    if npx jsii-diff $tmpdir/node_modules/${package_names[$i]} ${package_dirs[$i]} 2>$tmpdir/output.txt; then
+    if npx jsii-diff --experimental-errors $tmpdir/node_modules/${package_names[$i]} ${package_dirs[$i]} 2>$tmpdir/output.txt; then
         echo "OK."
     else
         success=false
diff --git a/vendored_deps/jsii-diff-0.12.x.tgz b/vendored_deps/jsii-diff-0.12.x.tgz
new file mode 100644
index 0000000000000..fbb15d4ca264b
Binary files /dev/null and b/vendored_deps/jsii-diff-0.12.x.tgz differ