diff --git a/pkgs/tools/networking/libreswan/default.nix b/pkgs/tools/networking/libreswan/default.nix
index b2024f55c4ea6..fd2461f517195 100644
--- a/pkgs/tools/networking/libreswan/default.nix
+++ b/pkgs/tools/networking/libreswan/default.nix
@@ -25,7 +25,12 @@ stdenv.mkDerivation {
   };
 
   # These flags were added to compile v3.18. Try to lift them when updating.
-  NIX_CFLAGS_COMPILE = [ "-Wno-error=redundant-decls" "-Wno-error=format-nonliteral" ];
+  NIX_CFLAGS_COMPILE = [ "-Wno-error=redundant-decls" "-Wno-error=format-nonliteral"
+    # these flags were added to build with gcc7
+    "-Wno-error=implicit-fallthrough"
+    "-Wno-error=format-truncation"
+    "-Wno-error=pointer-compare"
+  ];
 
   nativeBuildInputs = [ makeWrapper pkgconfig ];
   buildInputs = [ bash iproute iptables systemd coreutils gnused gawk gmp unbound bison flex pam libevent