diff --git a/test/other/codesize/test_codesize_cxx_except.size b/test/other/codesize/test_codesize_cxx_except.size
index 7a6716bb2a43a..16bb179be3c7a 100644
--- a/test/other/codesize/test_codesize_cxx_except.size
+++ b/test/other/codesize/test_codesize_cxx_except.size
@@ -1 +1 @@
-171008
+171030
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm.size b/test/other/codesize/test_codesize_cxx_except_wasm.size
index ccdf567408898..f63fa8e1ee181 100644
--- a/test/other/codesize/test_codesize_cxx_except_wasm.size
+++ b/test/other/codesize/test_codesize_cxx_except_wasm.size
@@ -1 +1 @@
-142223
+142234
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm_exnref.size b/test/other/codesize/test_codesize_cxx_except_wasm_exnref.size
index 9fd3641491ec2..bc2fc197a02a7 100644
--- a/test/other/codesize/test_codesize_cxx_except_wasm_exnref.size
+++ b/test/other/codesize/test_codesize_cxx_except_wasm_exnref.size
@@ -1 +1 @@
-144810
+144821
diff --git a/test/other/codesize/test_codesize_cxx_mangle.size b/test/other/codesize/test_codesize_cxx_mangle.size
index e1078b8c5934e..d6c1bcdbf748d 100644
--- a/test/other/codesize/test_codesize_cxx_mangle.size
+++ b/test/other/codesize/test_codesize_cxx_mangle.size
@@ -1 +1 @@
-232517
+232548
diff --git a/tools/system_libs.py b/tools/system_libs.py
index e6bbf1c3435b1..bbedd8ad00db4 100644
--- a/tools/system_libs.py
+++ b/tools/system_libs.py
@@ -42,6 +42,10 @@
 # link time.
 USE_NINJA = int(os.environ.get('EMCC_USE_NINJA', '0'))
 
+# A fake emscripten path to use in __FILE__ macro and debug info to produce
+# reproducible builds across platforms.
+FAKE_EMSCRIPTEN_PATH = '/emsdk/emscripten'
+
 
 def files_in_path(path, filenames):
   srcdir = utils.path_from_root(path)
@@ -472,9 +476,9 @@ def generate_ninja(self, build_dir, libname):
     if self.deterministic_paths:
       source_dir = utils.path_from_root()
       relative_source_dir = os.path.relpath(source_dir, build_dir)
-      cflags += [f'-ffile-prefix-map={source_dir}=/emsdk/emscripten',
-                 f'-ffile-prefix-map={relative_source_dir}/=',
-                 '-fdebug-compilation-dir=/emsdk/emscripten']
+      cflags += [f'-ffile-prefix-map={source_dir}={FAKE_EMSCRIPTEN_PATH}',
+                 f'-ffile-prefix-map={relative_source_dir}={FAKE_EMSCRIPTEN_PATH}',
+                 '-fdebug-compilation-dir={FAKE_EMSCRIPTEN_PATH}']
     asflags = get_base_cflags(preprocess=False)
     input_files = self.get_files()
     ninja_file = os.path.join(build_dir, 'build.ninja')
@@ -492,13 +496,14 @@ def build_objects(self, build_dir):
     commands = []
     objects = set()
     cflags = self.get_cflags()
-    if self.deterministic_paths:
+    if True:
+    #if self.deterministic_paths:
       source_dir = utils.path_from_root()
       if batch_inputs:
         relative_source_dir = os.path.relpath(source_dir, build_dir)
-        cflags += [f'-ffile-prefix-map={relative_source_dir}/=']
-      cflags += [f'-ffile-prefix-map={source_dir}=/emsdk/emscripten',
-                 '-fdebug-compilation-dir=/emsdk/emscripten']
+        cflags += [f'-ffile-prefix-map={relative_source_dir}={FAKE_EMSCRIPTEN_PATH}']
+      cflags += [f'-ffile-prefix-map={source_dir}={FAKE_EMSCRIPTEN_PATH}',
+                 '-fdebug-compilation-dir={FAKE_EMSCRIPTEN_PATH}']
     case_insensitive = is_case_insensitive(build_dir)
     for src in self.get_files():
       ext = shared.suffix(src)