diff --git a/log.py b/log.py
index ba91794..a5c2cd9 100644
--- a/log.py
+++ b/log.py
@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: MIT
 # Copyright 2021 Jookia <contact@jookia.org>
 
+import os
+
 LEXER = 0
 PARSER = 1
 
@@ -8,7 +10,12 @@
 DEBUG = 1 # high-level information about what's happening
 TRACE = 2 # trace output
 
+log_level = 0
+
 def log(module, level, text):
+    if level > log_level:
+        return
+
     if module == LEXER:
         module_name = "LEXER"
     elif module == PARSER:
@@ -26,3 +33,15 @@
         level_name = "UNKNOWN"
 
     print("%s %s: %s" % (level_name, module_name, text))
+
+def set_default_log_level():
+    level = os.getenv("NEWLANG_LOG_LEVEL")
+    global log_level
+    if not level or level == "NORMAL":
+        log_level = 0
+    elif level == "DEBUG":
+        log_level = 1
+    elif level == "TRACE":
+        log_level = 2
+    else:
+        print("ERROR: Unknown log level %s" % (level))
diff --git a/main.py b/main.py
index de28b1b..1ef46a5 100755
--- a/main.py
+++ b/main.py
@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: MIT
 # Copyright 2021 Jookia <contact@jookia.org>
 
+import log
 import parse
 
 def text_create(value):
@@ -78,6 +79,7 @@
     if len(args) != 2:
         print("Usage: main.py FILENAME")
         return 1
+    log.set_default_log_level()
     filename = args[1]
     code = open(filename).read()
     if code[0:2] == '#!':