diff --git a/configure.ac b/configure.ac
index 1e258a4..64de4bf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -235,8 +235,8 @@
 	CPPFLAGS+=" -fsanitize=address -fsanitize=undefined"
 fi
 
-CFLAGS+=" -DBUILDING_LIBOSMOCORE"
-CPPFLAGS+=" -DBUILDING_LIBOSMOCORE"
+CFLAGS+=" -DBUILDING_LIBOSMOCORE -Wall"
+CPPFLAGS+=" -DBUILDING_LIBOSMOCORE -Wall"
 
 AC_ARG_ENABLE(simd,
 	[AS_HELP_STRING(