diff --git a/pdf.c b/pdf.c
index 5795ee8129c4e08d153a4a8495353de6ff4a6da2..3e5e6303bf7b299acc1c4071f5c1e02f21ea313f 100644
--- a/pdf.c
+++ b/pdf.c
@@ -14,7 +14,7 @@
 #define IGN(P)		h_ignore(P)
 #define LIT(S)		h_ignore(h_literal(S))
 #define IN(STR)		h_in((const uint8_t *)(STR), sizeof(STR) - 1)
-#define NOT_IN(STR)	h_not_in((const uint8_t *)(STR), sizeof STR - 1)
+#define NOT_IN(STR)	h_not_in((const uint8_t *)(STR), sizeof(STR) - 1)
 
 
 /*