diff --git a/include/fmt/core.h b/include/fmt/core.h
index ee054cde..c0032b02 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -293,7 +293,7 @@
 
 // Enable minimal optimizations for more compact code in debug mode.
 FMT_GCC_PRAGMA("GCC push_options")
-#ifndef __OPTIMIZE__ && !FMT_NVHPC_VERSION
+#if !defined(__OPTIMIZE__) && !FMT_NVHPC_VERSION
 FMT_GCC_PRAGMA("GCC optimize(\"Og\")")
 #endif