diff --git a/tommath_class.h b/tommath_class.h
index 5fb50c82ad16b2bd341889420a7d15cc0594162b..4e54b5310791c294ebde44ad1d77e7d56f392669 100644
--- a/tommath_class.h
+++ b/tommath_class.h
@@ -57,10 +57,8 @@
 #define BN_MP_INVMOD_SLOW_C
 #define BN_MP_IS_SQUARE_C
 #define BN_MP_JACOBI_C
-/* matt - dropbear doesn't need these
 #define BN_MP_KARATSUBA_MUL_C
 #define BN_MP_KARATSUBA_SQR_C
-*/
 #define BN_MP_LCM_C
 #define BN_MP_LSHD_C
 #define BN_MP_MOD_C
@@ -108,10 +106,8 @@
 #define BN_MP_SUBMOD_C
 #define BN_MP_TO_SIGNED_BIN_C
 #define BN_MP_TO_UNSIGNED_BIN_C
-/* matt - dropbear doesn't need these
 #define BN_MP_TOOM_MUL_C
 #define BN_MP_TOOM_SQR_C
-*/
 #define BN_MP_TORADIX_C
 #define BN_MP_TORADIX_N_C
 #define BN_MP_UNSIGNED_BIN_SIZE_C
@@ -953,3 +949,9 @@
 #else
 #define LTM_LAST
 #endif
+
+/* Dropbear doesn't need these. */
+#undef BN_MP_KARATSUBA_MUL_C
+#undef BN_MP_KARATSUBA_SQR_C
+#undef BN_MP_TOOM_MUL_C
+#undef BN_MP_TOOM_SQR_C