diff --git a/libssh/base64.c b/libssh/base64.c
index 51563ef2..4c6f92d8 100644
--- a/libssh/base64.c
+++ b/libssh/base64.c
@@ -32,15 +32,15 @@ static char alphabet[]="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                         "abcdefghijklmnopqrstuvwxyz"
                         "0123456789+/" ;
 
-/* transformations */
-#define SET_A(n,i) do { n |= (i&63) <<18; } while (0)
-#define SET_B(n,i) do { n |= (i&63) <<12; } while (0)
-#define SET_C(n,i) do { n |= (i&63) << 6; } while (0)
-#define SET_D(n,i) do { n |= (i&63); } while (0)
+/* Transformations */
+#define SET_A(n, i) do { (n) |= ((i) & 63) <<18; } while (0)
+#define SET_B(n, i) do { (n) |= ((i) & 63) <<12; } while (0)
+#define SET_C(n, i) do { (n) |= ((i) & 63) << 6; } while (0)
+#define SET_D(n, i) do { (n) |= ((i) & 63); } while (0)
 
-#define GET_A(n) ((n & 0xff0000) >> 16)
-#define GET_B(n) ((n & 0xff00) >> 8)
-#define GET_C(n) (n & 0xff)
+#define GET_A(n) (((n) & 0xff0000) >> 16)
+#define GET_B(n) (((n) & 0xff00) >> 8)
+#define GET_C(n) ((n) & 0xff)
 
 static int _base64_to_bin(unsigned char dest[3], const char *source, int num);
 static int get_equals(char *string);