diff --git a/pkg/libcoap/Makefile b/pkg/libcoap/Makefile
index 1887f76b5e..e6cca7fcc5 100644
--- a/pkg/libcoap/Makefile
+++ b/pkg/libcoap/Makefile
@@ -12,3 +12,7 @@ all: git-download
 	"$(MAKE)" -C $(PKG_BUILDDIR)
 
 include $(RIOTBASE)/pkg/pkg.mk
+
+ifeq (llvm,$(TOOLCHAIN))
+  CFLAGS += -Wno-format-nonliteral
+endif