diff --git a/pkgs/by-name/el/elmerfem/package.nix b/pkgs/by-name/el/elmerfem/package.nix
index 820781d98759..6c467fc19761 100644
--- a/pkgs/by-name/el/elmerfem/package.nix
+++ b/pkgs/by-name/el/elmerfem/package.nix
@@ -58,6 +58,8 @@ stdenv.mkDerivation rec {
 
   storepath = placeholder "out";
 
+  NIX_CFLAGS_COMPILE = "-Wno-error=implicit-function-declaration";
+
   cmakeFlags = [
     "-DELMER_INSTALL_LIB_DIR=${storepath}/lib"
     "-DWITH_OpenMP:BOOLEAN=TRUE"