diff --git a/pdf.c b/pdf.c
index c6325722b033869d39e2520efd13b0c98ddada3e..6e6c6f61f8824b34174bc581978c6f58f7252482 100644
--- a/pdf.c
+++ b/pdf.c
@@ -262,7 +262,7 @@ act_hdigitpair(const HParseResult *p, void *u)
 	uint8_t b = 0;
 	HCountedArray *seq = H_CAST_SEQ(p->ast);
 	size_t digits_processed = 0;
-	uint8_t digits[2];
+	uint8_t digits[2] = {0, 0};
 	for(size_t i = 0; i < seq->used; ++i)
 	{
 		switch(seq->elements[i]->token_type)