diff --git a/mypy/util.py b/mypy/util.py
index e836aefb3c7ef..04ed616ade07d 100644
--- a/mypy/util.py
+++ b/mypy/util.py
@@ -520,7 +520,11 @@ def parse_gray_color(cup: bytes) -> str:
 
 
 def should_force_color() -> bool:
-    return bool(int(os.getenv("MYPY_FORCE_COLOR", os.getenv("FORCE_COLOR", "0"))))
+    env_var = os.getenv("MYPY_FORCE_COLOR", os.getenv("FORCE_COLOR", "0"))
+    try:
+        return bool(int(env_var))
+    except ValueError:
+        return bool(env_var)
 
 
 class FancyFormatter: