diff --git a/src/gen_context.c b/src/gen_context.c
index 024c557..0fb361f 100644
--- a/src/gen_context.c
+++ b/src/gen_context.c
@@ -13,6 +13,11 @@
 /* We can't require the precomputed tables when creating them. */
 #undef USE_ECMULT_STATIC_PRECOMPUTATION
 
+/* In principle we could use external ASM, but this yields only a minor speedup in
+   build time and it's very complicated. In particular when cross-compiling, we'd
+   need to build the external ASM for the build and the host machine. */
+#undef USE_EXTERNAL_ASM
+
 #include "include/secp256k1.h"
 #include "assumptions.h"
 #include "util.h"