diff --git a/include/mbedtls/gcm.h b/include/mbedtls/gcm.h
index a4de919..7dc9dfb 100644
--- a/include/mbedtls/gcm.h
+++ b/include/mbedtls/gcm.h
@@ -46,7 +46,7 @@
 /** Bad input parameters to function. */
 #define MBEDTLS_ERR_GCM_BAD_INPUT                         -0x0014
 /** An output buffer is too small. */
-#define MBEDTLS_ERR_GCM_BUFFER_TOO_SMALL                  -0x0018
+#define MBEDTLS_ERR_GCM_BUFFER_TOO_SMALL                  -0x0016
 
 #ifdef __cplusplus
 extern "C" {