diff --git a/pkgs/applications/science/math/nasc/default.nix b/pkgs/applications/science/math/nasc/default.nix
index 3fbcfecab06e..002acbf3875f 100644
--- a/pkgs/applications/science/math/nasc/default.nix
+++ b/pkgs/applications/science/math/nasc/default.nix
@@ -1,5 +1,6 @@
 { stdenv
 , fetchFromGitHub
+, fetchpatch
 , pkgconfig
 , vala
 , gtk3
@@ -25,6 +26,14 @@ stdenv.mkDerivation rec {
     sha256 = "036v3dx8yasp19j88lflibqnpfi5d0nk7qkcnr80zn1lvawf4wgn";
   };
 
+  patches = [
+    # fix build with gcc9
+    (fetchpatch {
+      url = "https://github.com/parnold-x/nasc/commit/46b9b80e228b6b86001bded45d85e073a9411549.patch";
+      sha256 = "1sm2aw0xhw2chk036r231nmp2f2ypxcmzggwljkn7wfzgg3h1mx3";
+    })
+  ];
+
   nativeBuildInputs = [
     cmake
     vala