diff --git a/src/util/macros.h b/src/util/macros.h
index af4c8c80b60..9403d337e49 100644
--- a/src/util/macros.h
+++ b/src/util/macros.h
@@ -122,17 +122,23 @@
 #if defined(HAVE___BUILTIN_UNREACHABLE) || __has_builtin(__builtin_unreachable)
 #define UNREACHABLE(str)    \
 do {                        \
-   assert(!"" str);         \
+   (void)"" str; /* str must be a string literal */ \
+   assert(!str);            \
    __builtin_unreachable(); \
 } while (0)
 #elif defined (_MSC_VER)
 #define UNREACHABLE(str)    \
 do {                        \
-   assert(!"" str);         \
+   (void)"" str; /* str must be a string literal */ \
+   assert(!str);            \
    __assume(0);             \
 } while (0)
 #else
-#define UNREACHABLE(str) assert(!"" str)
+#define UNREACHABLE(str)    \
+do {                        \
+   (void)"" str; /* str must be a string literal */ \
+   assert(!str);            \
+} while (0)
 #endif
 
 /**