diff --git a/crypto/sha512.c b/crypto/sha512.c
index 76250089c..b24a28ee0 100644
--- a/crypto/sha512.c
+++ b/crypto/sha512.c
@@ -54,7 +54,7 @@ static const uint8_t padding[128] PROGMEM =
     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
  
-static const uint64_t k[80] =
+static const uint64_t k[80] PROGMEM =
 {
     0x428A2F98D728AE22LL, 0x7137449123EF65CDLL, 0xB5C0FBCFEC4D3B2FLL, 0xE9B5DBA58189DBBCLL,
     0x3956C25BF348B538LL, 0x59F111F1B605D019LL, 0x923F82A4AF194F9BLL, 0xAB1C5ED5DA6D8118LL,