diff --git a/src/main/java/carpet/script/CarpetScriptHost.java b/src/main/java/carpet/script/CarpetScriptHost.java
index d3be9b6a..5c7bc1d2 100644
--- a/src/main/java/carpet/script/CarpetScriptHost.java
+++ b/src/main/java/carpet/script/CarpetScriptHost.java
@@ -1067,7 +1067,7 @@ public class CarpetScriptHost extends ScriptHost
     }
 
     @Override
-    public void handleExpressionException(String message, ExpressionException exc)
+    synchronized public void handleExpressionException(String message, ExpressionException exc)
     {
         handleErrorWithStack(message, new CarpetExpressionException(exc.getMessage(), exc.stack));
     }
diff --git a/src/main/java/carpet/script/ScriptHost.java b/src/main/java/carpet/script/ScriptHost.java
index 4d838c28..93b7dc35 100644
--- a/src/main/java/carpet/script/ScriptHost.java
+++ b/src/main/java/carpet/script/ScriptHost.java
@@ -344,7 +344,7 @@ public abstract class ScriptHost
         host.moduleData.forEach((module, data) -> data.setImportsBasedOn(host, this.moduleData.get(data.parent)));
     }
 
-    public void handleExpressionException(String msg, ExpressionException exc)
+    synchronized public void handleExpressionException(String msg, ExpressionException exc)
     {
         System.out.println(msg+": "+exc);
     }
diff --git a/src/main/java/carpet/script/exception/ExpressionException.java b/src/main/java/carpet/script/exception/ExpressionException.java
index a41cc178..b0872d05 100644
--- a/src/main/java/carpet/script/exception/ExpressionException.java
+++ b/src/main/java/carpet/script/exception/ExpressionException.java
@@ -70,7 +70,7 @@ public class ExpressionException extends RuntimeException implements ResolvedExc
         return errMsg;
     };
 
-    static String makeMessage(Context c, Expression e, Tokenizer.Token t, String message) throws ExpressionException
+    synchronized static String makeMessage(Context c, Expression e, Tokenizer.Token t, String message) throws ExpressionException
     {
         if (c.host.errorSnooper != null)
         {
diff --git a/src/main/java/carpet/script/value/ThreadValue.java b/src/main/java/carpet/script/value/ThreadValue.java
index b1105913..30c63555 100644
--- a/src/main/java/carpet/script/value/ThreadValue.java
+++ b/src/main/java/carpet/script/value/ThreadValue.java
@@ -44,7 +44,7 @@ public class ThreadValue extends Value
                         }
                         catch (ExpressionException exc)
                         {
-                            ctx.host.handleExpressionException("Thread failed", exc);
+                            ctx.host.handleExpressionException("Thread failed\n", exc);
                             return Value.NULL;
                         }