diff --git a/pkg/libcoap/Makefile b/pkg/libcoap/Makefile
index 4fc4944dcd..1887f76b5e 100644
--- a/pkg/libcoap/Makefile
+++ b/pkg/libcoap/Makefile
@@ -3,6 +3,9 @@ PKG_URL=https://github.com/obgm/libcoap
 PKG_VERSION=ef41ce5d02d64cec0751882ae8fd95f6c32bc018
 PKG_LICENSE=BSD-2-Clause
 
+# GCC 7.x fails on (intentional) fallthrough, thus disable implicit-fallthrough.
+CFLAGS += -Wno-implicit-fallthrough
+
 .PHONY: all
 
 all: git-download