diff --git a/Cargo.toml b/Cargo.toml
index 8c530db..ebc2ed4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "chacha20stream"
-version = "1.0.3"
+version = "1.2.0"
 keywords = ["chacha20_poly1305", "stream", "wrapper", "encryption", "decryption"]
 description = "A writable wrapper stream for encryption and decryption with the stream cipher chacha20_poly1305"
 homepage = "https://git.flanchan.moe/flanchan/chacha20stream"
@@ -28,7 +28,7 @@ async = ["tokio", "pin-project"]
 # Explicitly clear in-memory buffers with `explicit_bzero()` instead of normal `bzero()`.
 explicit_clear = []
 
-# Add C interface bindings
+# Build with C interface bindings
 ffi = ["libc"]
 
 [dependencies]
diff --git a/include/cc20.h b/include/cc20.h
index a462d24..020a45c 100644
--- a/include/cc20.h
+++ b/include/cc20.h
@@ -9,8 +9,19 @@ extern "C" {
 #include <stdint.h>
 #include <stddef.h>
 
-#define KEY_SIZE 32
-#define IV_SIZE 12
+/// CC20 C interface versioning macro.
+/// Most significant 8 bits is major, then next 8 is minor, then bugfix, then revision.
+/// The componants should never exceed 255, or that is undefined behaviour. They should also be unsigned int (uint32_t), or that is undefined behaviour. 
+/// This macro is not intended to be used.
+#define _CC20_VERSION(ma,mi,bu,r) (((ma) << 24) | ((mi) << 16) | ((bu) << 8) | (r))
+
+/// C interface API version
+#define CC20_C_API_VERSION 0
+/// The last library version as unsigned int. 
+#define CC20_MIN_LIBRARY_VERSION _CC20_VERSION(1u, 2u, 0, 0)
+
+#define CC20_KEY_SIZE 32
+#define CC20_IV_SIZE 12
 
 enum cc20_mode {
 	/// Encrypt the data written to this stream
@@ -40,9 +51,9 @@ typedef enum cc20_error {
 #define CC20_ERR(v) ((v)!=CC20_ERR_NONE)
 
 /// A chacha20_poly1305 key
-typedef uint8_t cc20_key_t[KEY_SIZE];
+typedef uint8_t cc20_key_t[CC20_KEY_SIZE];
 /// A chacha20_poly1305 IV
-typedef uint8_t cc20_iv_t[IV_SIZE];
+typedef uint8_t cc20_iv_t[CC20_IV_SIZE];
 
 /// Metadata used to construct an instance of `cc20_sink_t`.
 typedef struct cc20_metadata {
diff --git a/test.sh b/test.sh
index badc71a..b43c0f8 100755
--- a/test.sh
+++ b/test.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-gcc test.c -Iinclude -Wall --std=gnu11 -pedantic -Wextra -Og -g -o test-ffi -l:target/debug/libchacha20stream.a -lssl -lcrypto -lpthread -ldl || exit
+gcc test.c -Iinclude -Wall --std=gnu11 -pedantic -Wextra -Og -g -o test-ffi -l:target/release/libchacha20stream.a -lssl -lcrypto -lpthread -ldl || exit
 valgrind ./test-ffi # test-ffi-output
 #hexview test-ffi-output
 rm -f test-ffi{,-output}