diff --git a/aes.c b/aes.c
index 8fd0a85..3e0b3e3 100644
--- a/aes.c
+++ b/aes.c
@@ -226,7 +226,7 @@ void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key)
 {
   KeyExpansion(ctx->RoundKey, key);
 }
-#if defined(CBC) && (CBC == 1)
+#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
 void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv)
 {
   KeyExpansion(ctx->RoundKey, key);
diff --git a/aes.h b/aes.h
index a57a2f0..dd16622 100644
--- a/aes.h
+++ b/aes.h
@@ -49,7 +49,7 @@ struct AES_ctx
 };
 
 void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key);
-#if defined(CBC) && (CBC == 1)
+#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
 void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv);
 void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv);
 #endif