diff --git a/test/de/inetsoftware/jwebassembly/WasmRule.java b/test/de/inetsoftware/jwebassembly/WasmRule.java
index 52fcccc..d9309c2 100644
--- a/test/de/inetsoftware/jwebassembly/WasmRule.java
+++ b/test/de/inetsoftware/jwebassembly/WasmRule.java
@@ -548,7 +548,7 @@ public class WasmRule extends TemporaryFolder {
             compiler.setProperty( JWebAssembly.WASM_USE_GC, null );
             System.clearProperty( "SpiderMonkey" );
         }
-        ProcessBuilder process = new ProcessBuilder( spiderMonkey.getCommand(), /*"--wasm-bigint",*/ script.getAbsolutePath() );
+        ProcessBuilder process = new ProcessBuilder( spiderMonkey.getCommand(), "--wasm-bigint", script.getAbsolutePath() );
         if( gc ) {
             process.command().add( 1, "--wasm-gc" );
         }
diff --git a/test/de/inetsoftware/jwebassembly/runtime/ArrayOperations.java b/test/de/inetsoftware/jwebassembly/runtime/ArrayOperations.java
index 4ac93e3..e0967e3 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/ArrayOperations.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/ArrayOperations.java
@@ -67,8 +67,6 @@ public class ArrayOperations extends AbstractBaseTest {
     @Test
     @Override
     public void test() {
-        Assume.assumeFalse( (getScriptEngine().name().startsWith( "SpiderMonkey" ) )
-                        && "loopLong".equals( getMethod() ) ); // TODO SpiderMonkey https://bugzilla.mozilla.org/show_bug.cgi?id=1511958
         Assume.assumeFalse( getScriptEngine().name().endsWith( "GC" ) );
         super.test();
     }
diff --git a/test/de/inetsoftware/jwebassembly/runtime/DynamicValues.java b/test/de/inetsoftware/jwebassembly/runtime/DynamicValues.java
index 599da1d..fe700c2 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/DynamicValues.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/DynamicValues.java
@@ -56,7 +56,6 @@ public class DynamicValues {
 
     @Test
     public void currentTimeMillis() {
-        assumeFalse( script == ScriptEngine.SpiderMonkey || script == ScriptEngine.SpiderMonkeyWat );
         long before = System.currentTimeMillis(); 
         String result = rule.evalWasm( script, "currentTimeMillis" );
         long after = System.currentTimeMillis(); 
diff --git a/test/de/inetsoftware/jwebassembly/runtime/MathAPI.java b/test/de/inetsoftware/jwebassembly/runtime/MathAPI.java
index 197ff8d..fd2b876 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/MathAPI.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/MathAPI.java
@@ -235,15 +235,13 @@ public class MathAPI extends AbstractBaseTest {
         }
 
         @Export
-        static int roundD3_8() {
-            // SpiderMonkey does not support BigInt currently
-            return (int)Math.round( 3.8 );
+        static long roundD3_8() {
+            return Math.round( 3.8 );
         }
 
         @Export
-        static int roundD_3_8() {
-            // SpiderMonkey does not support BigInt currently
-            return (int)Math.round( -3.8 );
+        static long roundD_3_8() {
+            return Math.round( -3.8 );
         }
 
         @Export
diff --git a/test/de/inetsoftware/jwebassembly/runtime/RuntimeErrors.java b/test/de/inetsoftware/jwebassembly/runtime/RuntimeErrors.java
index 154ac94..52fd6c2 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/RuntimeErrors.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/RuntimeErrors.java
@@ -15,15 +15,12 @@
  */
 package de.inetsoftware.jwebassembly.runtime;
 
-import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
-import static org.junit.Assume.assumeTrue;
 
 import java.io.IOException;
 import java.util.Collection;
 
-import org.junit.ClassRule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
@@ -41,9 +38,6 @@ import de.inetsoftware.jwebassembly.api.annotation.Import;
 @RunWith( Parameterized.class )
 public class RuntimeErrors {
 
-    @ClassRule
-    public static WasmRule     rule = new WasmRule( TestClass.class );
-
     private final ScriptEngine script;
 
     public RuntimeErrors( ScriptEngine script ) {
@@ -55,26 +49,6 @@ public class RuntimeErrors {
         return ScriptEngine.testParams();
     }
 
-    @Test
-    public void longReturn() {
-        assumeTrue( script == ScriptEngine.SpiderMonkey || script == ScriptEngine.SpiderMonkeyWat );
-        String error = rule.evalWasm( script, "longReturn" );
-        int newlineIdx = error.indexOf( '\n' );
-        if( newlineIdx > 0 ) {
-            error = error.substring( 0, newlineIdx );
-        }
-        String expected = "TypeError: cannot pass i64 to or from JS";
-        assertEquals( expected, error );
-    }
-
-    static class TestClass {
-
-        @Export
-        static long longReturn() {
-            return Long.MAX_VALUE;
-        }
-    }
-
     private void compileErrorTest( String expectedMessge, Class<?> classes ) throws IOException {
         WasmRule wasm = new WasmRule( classes );
         try {