diff --git a/ecdsa.h b/ecdsa.h
index e86a038..01cb134 100644
--- a/ecdsa.h
+++ b/ecdsa.h
@@ -16,7 +16,7 @@
 #elif DROPBEAR_ECC_521
 #define ECDSA_DEFAULT_SIZE 521
 #else
-#error ECDSA can't be enabled without enabling at least one size (256, 384, 521)
+#error ECDSA cannot be enabled without enabling at least one size (256, 384, 521)
 #endif
 
 ecc_key *gen_ecdsa_priv_key(unsigned int bit_size);