diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 624228914e..49c312082d 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -123,11 +123,13 @@ extern "C" {
 #define MBEDTLS_ERROR_ADD( high, low ) \
         mbedtls_error_add_ext( high, low, __FILE__, __LINE__ )
 
+#if defined(MBEDTLS_TEST_HOOKS)
 /**
  * \brief Testing hook called before adding/combining two error codes together.
  *        Only used when invasive testing is enabled via MBEDTLS_TEST_HOOKS.
  */
 extern void (*mbedtls_test_hook_error_add)( int, int, const char *, int );
+#endif
 
 /**
  * \brief Combines a high-level and low-level error code together.
diff --git a/library/error.c b/library/error.c
index b5bd8d77c3..afad38904f 100644
--- a/library/error.c
+++ b/library/error.c
@@ -893,8 +893,6 @@ const char * mbedtls_low_level_strerr( int error_code )
     return( NULL );
 }
 
-void (*mbedtls_test_hook_error_add)( int, int, const char *, int );
-
 void mbedtls_strerror( int ret, char *buf, size_t buflen )
 {
     size_t len;
@@ -975,4 +973,8 @@ void mbedtls_strerror( int ret, char *buf, size_t buflen )
 
 #endif /* MBEDTLS_ERROR_C */
 
+#if defined(MBEDTLS_TEST_HOOKS)
+void (*mbedtls_test_hook_error_add)( int, int, const char *, int );
+#endif
+
 #endif /* MBEDTLS_ERROR_C || MBEDTLS_ERROR_STRERROR_DUMMY */
diff --git a/scripts/data_files/error.fmt b/scripts/data_files/error.fmt
index 7fed598eaf..3be94bd2c4 100644
--- a/scripts/data_files/error.fmt
+++ b/scripts/data_files/error.fmt
@@ -82,8 +82,6 @@ LOW_LEVEL_CODE_CHECKS
     return( NULL );
 }
 
-void (*mbedtls_test_hook_error_add)( int, int, const char *, int );
-
 void mbedtls_strerror( int ret, char *buf, size_t buflen )
 {
     size_t len;
@@ -164,4 +162,8 @@ void mbedtls_strerror( int ret, char *buf, size_t buflen )
 
 #endif /* MBEDTLS_ERROR_C */
 
+#if defined(MBEDTLS_TEST_HOOKS)
+void (*mbedtls_test_hook_error_add)( int, int, const char *, int );
+#endif
+
 #endif /* MBEDTLS_ERROR_C || MBEDTLS_ERROR_STRERROR_DUMMY */