diff --git a/hwmonio.cpp b/hwmonio.cpp
index 82d1a9d..8f0acf2 100644
--- a/hwmonio.cpp
+++ b/hwmonio.cpp
@@ -150,7 +150,7 @@
                 !retries)
             {
                 // Not a retryable error or out of retries.
-#ifdef NEGATIVE_ERRNO_ON_FAIL
+#if NEGATIVE_ERRNO_ON_FAIL
                 return -rc;
 #endif