diff --git a/libdex/sha1.cpp b/libdex/sha1.cpp
index 60c4d93..e1a7a04 100644
--- a/libdex/sha1.cpp
+++ b/libdex/sha1.cpp
@@ -116,15 +116,15 @@
 #else
 #define blk0(i) block->l[i]
 #endif
-#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
-    ^block->l[(i+2)&15]^block->l[i&15],1))
+#define blk(i) (block->l[(i)&15] = rol(block->l[((i)+13)&15]^block->l[((i)+8)&15] \
+    ^block->l[((i)+2)&15]^block->l[(i)&15],1))
 
 /* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
-#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5);w=rol(w,30);
-#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
-#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
-#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
-#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);
+#define R0(v,w,x,y,z,i) z+=(((w)&((x)^(y)))^(y))+blk0(i)+0x5A827999+rol(v,5);(w)=rol(w,30);
+#define R1(v,w,x,y,z,i) z+=(((w)&((x)^(y)))^(y))+blk(i)+0x5A827999+rol(v,5);(w)=rol(w,30);
+#define R2(v,w,x,y,z,i) z+=((w)^(x)^(y))+blk(i)+0x6ED9EBA1+rol(v,5);(w)=rol(w,30);
+#define R3(v,w,x,y,z,i) z+=((((w)|(x))&(y))|((w)&(x)))+blk(i)+0x8F1BBCDC+rol(v,5);(w)=rol(w,30);
+#define R4(v,w,x,y,z,i) z+=((w)^(x)^(y))+blk(i)+0xCA62C1D6+rol(v,5);(w)=rol(w,30);
 
 
 /* Hash a single 512-bit block. This is the core of the algorithm. */