diff --git a/pkg/monocypher/Makefile.dep b/pkg/monocypher/Makefile.dep
index 767f3cc1c7..2a90b71378 100644
--- a/pkg/monocypher/Makefile.dep
+++ b/pkg/monocypher/Makefile.dep
@@ -1 +1,4 @@
 USEMODULE += monocypher_sha512
+
+# monocypher is only supported by 32 bit architectures
+FEATURES_REQUIRED += arch_32bit