diff --git a/pdf.c b/pdf.c
index dec14d8977aebe130acd46c2fe03cf964aa8cdad..c05670a05e15cb24a1278d40cd5b26f2699c1924 100644
--- a/pdf.c
+++ b/pdf.c
@@ -257,7 +257,7 @@ act_a85digit(const HParseResult *p, void *u)
 HParsedToken *
 act_a85group(const HParseResult *p, void *u)
 {
-	uint64_t b = 0;
+	uint64_t fourbytes = 0;
 	HCountedArray *seq = H_CAST_SEQ(p->ast);
 	HParsedToken **digits = h_seq_elements(p->ast);
 
@@ -266,17 +266,17 @@ act_a85group(const HParseResult *p, void *u)
 
 	/* Only for groups that do not need to padded to 5 */
 	assert(seq->used == 5);
-	b += H_CAST_UINT(digits[0]) * ((uint64_t) pow(85,4));
-	b += H_CAST_UINT(digits[1]) * ((uint64_t) pow(85,3));
-	b += H_CAST_UINT(digits[2]) * ((uint64_t) pow(85,2));
-	b += H_CAST_UINT(digits[3]) * ((uint64_t) pow(85,1));
-	b += H_CAST_UINT(digits[4]);
+	fourbytes += H_CAST_UINT(digits[0]) * ((uint64_t) pow(85,4));
+	fourbytes += H_CAST_UINT(digits[1]) * ((uint64_t) pow(85,3));
+	fourbytes += H_CAST_UINT(digits[2]) * ((uint64_t) pow(85,2));
+	fourbytes += H_CAST_UINT(digits[3]) * ((uint64_t) pow(85,1));
+	fourbytes += H_CAST_UINT(digits[4]);
 
-	assert(b <= A85GRPMAX);
+	assert(fourbytes <= A85GRPMAX);
 	// XXX make it generic with H_ACT_APPLY
 	// XXX but partial groups are at least 2 characters long
 
-	return H_MAKE_UINT(b);
+	return H_MAKE_UINT(fourbytes);
 }
 
 HParsedToken *