diff --git a/Makefile.all.am b/Makefile.all.am
index 44b024a..3b2772a 100644
--- a/Makefile.all.am
+++ b/Makefile.all.am
@@ -98,6 +98,7 @@
 # that somehow causes VG_(memset) to get into infinite recursion.
 AM_CFLAGS_BASE = \
 	-O2 -g \
+	-std=gnu99 \
 	-Wall \
 	-Wcast-align \
 	-Wmissing-prototypes \
@@ -105,7 +106,6 @@
 	-Wpointer-arith \
 	-Wstrict-prototypes \
 	-Wmissing-declarations \
-	-Wno-long-long \
 	@FLAG_W_CAST_QUAL@ \
 	@FLAG_W_WRITE_STRINGS@ \
 	@FLAG_W_FORMAT@ \