diff --git a/pkg/spiffs/Makefile b/pkg/spiffs/Makefile
index 7de6d0c840..4fd62bdb01 100644
--- a/pkg/spiffs/Makefile
+++ b/pkg/spiffs/Makefile
@@ -3,8 +3,6 @@ PKG_URL=https://github.com/pellepl/spiffs.git
 PKG_VERSION=287148c46587089c4543a21eef2d6e9e14b88364
 PKG_LICENSE=MIT
 
-CFLAGS += -std=c11
-
 .PHONY: all
 
 all: git-download
diff --git a/pkg/spiffs/Makefile.spiffs b/pkg/spiffs/Makefile.spiffs
index 4e8962d731..1cb6ab8c0b 100644
--- a/pkg/spiffs/Makefile.spiffs
+++ b/pkg/spiffs/Makefile.spiffs
@@ -1,3 +1,6 @@
 MODULE := spiffs
 
+# Disable 'ISO C99 doesn’t support unnamed structs/unions [-Werror=pedantic]'
+CFLAGS += -Wno-pedantic
+
 include $(RIOTBASE)/Makefile.base