diff --git a/src/libgcrypt.h b/src/libgcrypt.h
index a5366f9..d925700 100644
--- a/src/libgcrypt.h
+++ b/src/libgcrypt.h
@@ -63,7 +63,7 @@
 #define libssh2_sha1_init(ctx) gcry_md_open (ctx,  GCRY_MD_SHA1, 0);
 #define libssh2_sha1_update(ctx, data, len) gcry_md_write (ctx, data, len)
 #define libssh2_sha1_final(ctx, out) \
-  memcpy (out, gcry_md_read (ctx, 0), 20), gcry_md_close (ctx)
+  memcpy (out, gcry_md_read (ctx, 0), SHA_DIGEST_LENGTH), gcry_md_close (ctx)
 #define libssh2_sha1(message, len, out) \
   gcry_md_hash_buffer (GCRY_MD_SHA1, out, message, len)
 
@@ -71,7 +71,7 @@
 #define libssh2_md5_init(ctx) gcry_md_open (ctx,  GCRY_MD_MD5, 0);
 #define libssh2_md5_update(ctx, data, len) gcry_md_write (ctx, data, len)
 #define libssh2_md5_final(ctx, out) \
-  memcpy (out, gcry_md_read (ctx, 0), 20), gcry_md_close (ctx)
+  memcpy (out, gcry_md_read (ctx, 0), MD5_DIGEST_LENGTH), gcry_md_close (ctx)
 #define libssh2_md5(message, len, out) \
   gcry_md_hash_buffer (GCRY_MD_MD5, out, message, len)