diff --git a/app/tsl2561/Makefile b/app/tsl2561/Makefile
index 34d6e7dc..7963bd5d 100644
--- a/app/tsl2561/Makefile
+++ b/app/tsl2561/Makefile
@@ -15,6 +15,7 @@ ifndef PDIR
 GEN_LIBS = tsl2561lib.a
 endif
 
+STD_CFLAGS=-std=gnu11 -Wimplicit
 
 #############################################################
 # Configuration i.e. compile options etc.
diff --git a/app/u8glib/Makefile b/app/u8glib/Makefile
index 72a951e7..7495a1d7 100644
--- a/app/u8glib/Makefile
+++ b/app/u8glib/Makefile
@@ -15,6 +15,8 @@ ifndef PDIR
 GEN_LIBS = u8glib.a
 endif
 
+STD_CFLAGS=-std=gnu11 -Wimplicit
+
 #############################################################
 # Configuration i.e. compile options etc.
 # Target specific stuff (defines etc.) goes in here!
diff --git a/app/ucglib/Makefile b/app/ucglib/Makefile
index 843676ab..6a9c929b 100644
--- a/app/ucglib/Makefile
+++ b/app/ucglib/Makefile
@@ -15,6 +15,8 @@ ifndef PDIR
 GEN_LIBS = ucglib.a
 endif
 
+STD_CFLAGS=-std=gnu11 -Wimplicit
+
 #############################################################
 # Configuration i.e. compile options etc.
 # Target specific stuff (defines etc.) goes in here!