diff --git a/src/libCom/osi/os/posix/epicsMath.h b/src/libCom/osi/os/posix/epicsMath.h
index 7cd0bb409..4e558676c 100644
--- a/src/libCom/osi/os/posix/epicsMath.h
+++ b/src/libCom/osi/os/posix/epicsMath.h
@@ -19,7 +19,7 @@ extern "C" {
 
 #ifdef isfinite
 #  undef finite
-#  define finite(x) isfinite((double)x)
+#  define finite(x) isfinite((double)(x))
 #endif
 
 epicsShareExtern float epicsNAN;