diff --git a/pkgs/applications/networking/browsers/firefox/default.nix b/pkgs/applications/networking/browsers/firefox/default.nix
index b7ebe44484e..5ce5acde83f 100644
--- a/pkgs/applications/networking/browsers/firefox/default.nix
+++ b/pkgs/applications/networking/browsers/firefox/default.nix
@@ -36,7 +36,7 @@ stdenv.mkDerivation {
     "--with-system-jpeg"
     "--with-system-png"
     "--with-system-zlib"
-    "--with-system-cairo"
+    "--enable-system-cairo"
   ]
   ++ (if enableOfficialBranding then ["--enable-official-branding"] else []);
 
diff --git a/pkgs/applications/networking/mailreaders/thunderbird/default.nix b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
index 2ae53f53518..acccca4d7cf 100644
--- a/pkgs/applications/networking/mailreaders/thunderbird/default.nix
+++ b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
@@ -37,7 +37,7 @@ stdenv.mkDerivation {
     "--with-system-jpeg"
     "--with-system-png"
     "--with-system-zlib"
-    "--with-system-cairo"
+    "--enable-system-cairo"
   ]
   ++ (if enableOfficialBranding then ["--enable-official-branding"] else []);
 }