diff --git a/components/image/gthumb/Makefile b/components/image/gthumb/Makefile
index 915f5488086..51ce21d6324 100644
--- a/components/image/gthumb/Makefile
+++ b/components/image/gthumb/Makefile
@@ -37,6 +37,7 @@ PATH=$(PATH.gnu)
 
 COMPONENT_PREP_ACTION = (cd $(@D) && autoreconf -fi)
 
+CFLAGS   += -std=gnu89 -D_XOPEN_SOURCE=500
 CPPFLAGS += -I/usr/include/lcms2
 
 # Use default libjpeg