diff --git a/include/criterion/assert.h b/include/criterion/assert.h
index 3c69283..fee1d4e 100644
--- a/include/criterion/assert.h
+++ b/include/criterion/assert.h
@@ -30,12 +30,6 @@
 
 # include "internal/assert.h"
 
-CR_BEGIN_C_API
-
-CR_API char *cr_translate_assert_msg(int msg_index, ...);
-
-CR_END_C_API
-
 // Base assertions
 
 # define cr_assert_fail(...) CR_EXPAND(cr_fail(CR_FAIL_ABORT_,     __VA_ARGS__))
diff --git a/include/criterion/internal/assert.h b/include/criterion/internal/assert.h
index 426e3ae..fd79d79 100644
--- a/include/criterion/internal/assert.h
+++ b/include/criterion/internal/assert.h
@@ -70,6 +70,12 @@ enum criterion_assert_messages {
     CRITERION_ASSERT_MSG_NONE_THROW,
 };
 
+CR_BEGIN_C_API
+
+CR_API char *cr_translate_assert_msg(int msg_index, ...);
+
+CR_END_C_API
+
 # define CR_GET_CONDITION(Condition, ...) Condition
 # define CR_GET_CONDITION_STR(Condition, ...) #Condition
 # define CR_VA_SKIP(_, ...) __VA_ARGS__