diff --git a/lang/ninja/src/build.sld b/lang/ninja/src/build.sld
index 0469b54..92d8e96 100644
--- a/lang/ninja/src/build.sld
+++ b/lang/ninja/src/build.sld
@@ -329,6 +329,7 @@
   (define (can-safely-elide-header path)
    (or
     (string-suffix? ".hh" path)
+    (string-suffix? ".hpp" path)
     (string-suffix? ".h" path)))
 
   ;; process a ninja file and corresponding vfs, and return two values:
diff --git a/lang/ninja/src/nixpkgs.sld b/lang/ninja/src/nixpkgs.sld
index 5032a2a..f49672d 100644
--- a/lang/ninja/src/nixpkgs.sld
+++ b/lang/ninja/src/nixpkgs.sld
@@ -278,7 +278,7 @@
           "zilchPlace() {\n"
            "cd $NIX_BUILD_TOP; cp -rf --no-preserve=ownership " #$realised-store " bdir\n"
            "chmod ugo+rw -R bdir\n"
-           "(cd " #$realised-store "/src; find . -type f '(' -name '*.h' -o -name '*.hh' -o -name '*.so' ')') | while read f; do zilchMakeFile \"../src/$f\"; done\n"
+           "(cd " #$realised-store "/src; find . -type f '(' -name '*.h' -o -name '*.hh' -o -name '*.hpp' -o -name '*.so' ')') | while read f; do zilchMakeFile \"../src/$f\"; done\n"
            make-all-placeholder-files
            "cd bdir/build\n"
           "}\n"