diff --git a/library/havege.c b/library/havege.c
index 4dcac02..54f897c 100644
--- a/library/havege.c
+++ b/library/havege.c
@@ -54,7 +54,7 @@
  * ------------------------------------------------------------------------
  */
 
-#define SWAP(X,Y) { int *T = X; X = Y; Y = T; }
+#define SWAP(X,Y) { int *T = (X); (X) = (Y); (Y) = T; }
 
 #define TST1_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;
 #define TST2_ENTER if( PTEST & 1 ) { PTEST ^= 3; PTEST >>= 1;