diff --git a/library/bignum_mod_raw.c b/library/bignum_mod_raw.c
index aa2bd46..b232182 100644
--- a/library/bignum_mod_raw.c
+++ b/library/bignum_mod_raw.c
@@ -128,6 +128,21 @@
                              N->rep.mont.mm, T);
 }
 
+MBEDTLS_STATIC_TESTABLE
+int mbedtls_mpi_mod_raw_fix_quasi_reduction(mbedtls_mpi_uint *X,
+                                            const mbedtls_mpi_mod_modulus *N)
+{
+    if (N->limbs == 0) {
+        return MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
+    }
+
+    mbedtls_mpi_uint c = mbedtls_mpi_core_sub(X, X, N->p, N->limbs);
+
+    (void) mbedtls_mpi_core_add_if(X, N->p, N->limbs, (unsigned) c);
+
+    return 0;
+}
+
 /* END MERGE SLOT 2 */
 
 /* BEGIN MERGE SLOT 3 */
diff --git a/library/ecp_internal.h b/library/bignum_mod_raw_invasive.h
similarity index 73%
rename from library/ecp_internal.h
rename to library/bignum_mod_raw_invasive.h
index b028225..3d4afed 100644
--- a/library/ecp_internal.h
+++ b/library/bignum_mod_raw_invasive.h
@@ -1,8 +1,8 @@
 /**
- * \file ecp_internal.h
+ * \file bignum_mod_raw_invasive.h
  *
- * \brief Function declarations for internal functions of elliptic curve
- * point arithmetic.
+ * \brief Function declarations for invasive functions of Low-level
+ *        modular bignum.
  */
 /**
  *  Copyright The Mbed TLS Contributors
@@ -21,8 +21,8 @@
  *  limitations under the License.
  */
 
-#ifndef MBEDTLS_ECP_INTERNAL_H
-#define MBEDTLS_ECP_INTERNAL_H
+#ifndef MBEDTLS_BIGNUM_MOD_RAW_INVASIVE_H
+#define MBEDTLS_BIGNUM_MOD_RAW_INVASIVE_H
 
 #include "common.h"
 #include "mbedtls/bignum.h"
@@ -40,7 +40,8 @@
  * \return      \c 0 if successful.
  * \return      #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p N is invalid.
  */
-int mbedtls_ecp_quasi_reduction(mbedtls_mpi_uint *X,
-                                const mbedtls_mpi_mod_modulus *N);
+MBEDTLS_STATIC_TESTABLE
+int mbedtls_mpi_mod_raw_fix_quasi_reduction(mbedtls_mpi_uint *X,
+                                            const mbedtls_mpi_mod_modulus *N);
 
-#endif /* MBEDTLS_ECP_INTERNAL_H */
+#endif /* MBEDTLS_BIGNUM_MOD_RAW_INVASIVE_H */
diff --git a/library/ecp.c b/library/ecp.c
index 835bfa3..6f53c1b 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -79,7 +79,6 @@
 
 #include "bn_mul.h"
 #include "ecp_invasive.h"
-#include "ecp_internal.h"
 #include "bignum_core.h"
 
 #include <string.h>
@@ -1031,20 +1030,6 @@
     return ret;
 }
 
-int mbedtls_ecp_quasi_reduction(mbedtls_mpi_uint *X,
-                                const mbedtls_mpi_mod_modulus *N)
-{
-    if (N->limbs == 0) {
-        return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
-    }
-
-    mbedtls_mpi_uint c = mbedtls_mpi_core_sub(X, X, N->p, N->limbs);
-
-    (void) mbedtls_mpi_core_add_if(X, N->p, N->limbs, (unsigned) c);
-
-    return 0;
-}
-
 /*
  * Fast mod-p functions expect their argument to be in the 0..p^2 range.
  *