diff --git a/.circleci/osx_install_dependencies.sh b/.circleci/osx_install_dependencies.sh
index 1cc16a9c9..64a83f56b 100755
--- a/.circleci/osx_install_dependencies.sh
+++ b/.circleci/osx_install_dependencies.sh
@@ -55,5 +55,9 @@ then
   wget https://github.com/ethereum/evmone/releases/download/v0.4.0/evmone-0.4.0-darwin-x86_64.tar.gz
   tar xzpf evmone-0.4.0-darwin-x86_64.tar.gz -C /usr/local
   rm -f evmone-0.4.0-darwin-x86_64.tar.gz
-fi
 
+  # hera
+  wget https://github.com/ewasm/hera/releases/download/v0.3.0/hera-0.3.0-darwin-x86_64.tar.gz
+  tar xzpf hera-0.3.0-darwin-x86_64.tar.gz -C /usr/local
+  rm -f hera-0.3.0-darwin-x86_64.tar.gz
+fi
diff --git a/.circleci/soltest_all.sh b/.circleci/soltest_all.sh
index 78cc1137d..02b675aa1 100755
--- a/.circleci/soltest_all.sh
+++ b/.circleci/soltest_all.sh
@@ -69,7 +69,11 @@ for OPTIMIZE in ${OPTIMIZE_VALUES[@]}
 do
     for EVM in ${EVM_VALUES[@]}
     do
-        [[ " $RUN_STEPS " =~ " $STEP " ]] && EVM="$EVM" OPTIMIZE="$OPTIMIZE" BOOST_TEST_ARGS="-t !@nooptions" "${REPODIR}/.circleci/soltest.sh"
+        # run tests against hera ewasm evmc vm, only if OPTIMIZE == 0 and evm version is byzantium
+        EWASM_ARGS=""
+        [ "${EVM}" = "byzantium" ] && [ "${OPTIMIZE}" = "0" ] && EWASM_ARGS="--ewasm"
+
+        [[ " $RUN_STEPS " =~ " $STEP " ]] && EVM="$EVM" OPTIMIZE="$OPTIMIZE" SOLTEST_FLAGS="$SOLTEST_FLAGS $EWASM_ARGS" BOOST_TEST_ARGS="-t !@nooptions" "${REPODIR}/.circleci/soltest.sh"
         STEP=$(($STEP + 1))
     done
 done
diff --git a/scripts/tests.sh b/scripts/tests.sh
index 00b4a1641..8bb08d963 100755
--- a/scripts/tests.sh
+++ b/scripts/tests.sh
@@ -115,8 +115,11 @@ do
                 fi
             fi
 
+            EWASM_ARGS=""
+            [ "${vm}" = "byzantium" ] && [ "${optimize}" = "" ] && EWASM_ARGS="--ewasm"
+
             set +e
-            "${SOLIDITY_BUILD_DIR}"/test/soltest --show-progress $log -- --testpath "$REPO_ROOT"/test "$optimize" --evm-version "$vm" $SMT_FLAGS $force_abiv2_flag
+            "${SOLIDITY_BUILD_DIR}"/test/soltest --show-progress $log -- ${EWASM_ARGS} --testpath "$REPO_ROOT"/test "$optimize" --evm-version "$vm" $SMT_FLAGS $force_abiv2_flag
 
             if test "0" -ne "$?"; then
                 exit 1