diff --git a/upstream_utils/libuv.py b/upstream_utils/libuv.py
index 9a2865838c..73ba5f6830 100755
--- a/upstream_utils/libuv.py
+++ b/upstream_utils/libuv.py
@@ -51,6 +51,7 @@ def copy_upstream_src(wpilib_root):
     src_files = walk_cwd_and_copy_if(
         lambda dp, f: dp.startswith("./src") and f not in src_ignorelist,
         os.path.join(wpinet, "src/main/native/thirdparty/libuv"),
+        rename_c_to_cpp=True,
     )
 
 
diff --git a/upstream_utils/mpack.py b/upstream_utils/mpack.py
index ad395377a6..e0971f3079 100755
--- a/upstream_utils/mpack.py
+++ b/upstream_utils/mpack.py
@@ -39,6 +39,7 @@ def copy_upstream_src(wpilib_root):
     walk_cwd_and_copy_if(
         lambda dp, f: f.endswith(".c"),
         os.path.join(wpiutil, "src/main/native/thirdparty/mpack/src"),
+        rename_c_to_cpp=True,
     )
 
 
diff --git a/upstream_utils/upstream_utils.py b/upstream_utils/upstream_utils.py
index 5851df11f9..7fc287ba0b 100644
--- a/upstream_utils/upstream_utils.py
+++ b/upstream_utils/upstream_utils.py
@@ -87,7 +87,7 @@ def walk_if(top, pred):
     ]
 
 
-def copy_to(files, root):
+def copy_to(files, root, rename_c_to_cpp=False):
     """Copies list of files to root by appending the relative paths of the files
     to root.
 
@@ -96,6 +96,7 @@ def copy_to(files, root):
     Keyword arguments:
     files -- list of files to copy
     root -- destination
+    rename_c_to_cpp -- whether to rename .c files to .cpp (default: False)
 
     Returns:
     The list of files in their destination.
@@ -110,7 +111,7 @@ def copy_to(files, root):
         # Rename .cc file to .cpp
         if dest_file.endswith(".cc"):
             dest_file = os.path.splitext(dest_file)[0] + ".cpp"
-        if dest_file.endswith(".c"):
+        if rename_c_to_cpp and dest_file.endswith(".c"):
             dest_file = os.path.splitext(dest_file)[0] + ".cpp"
 
         # Make leading directory
@@ -123,7 +124,7 @@ def copy_to(files, root):
     return dest_files
 
 
-def walk_cwd_and_copy_if(pred, root):
+def walk_cwd_and_copy_if(pred, root, rename_c_to_cpp=False):
     """Walks the current directory, generates a list of files for which the
     given predicate is true, then copies that list to root by appending the
     relative paths of the files to root.
@@ -134,12 +135,13 @@ def walk_cwd_and_copy_if(pred, root):
     pred -- a function that takes a directory path and a filename, then returns
             True if the file should be included in the output list
     root -- destination
+    rename_c_to_cpp -- whether to rename .c files to .cpp (default: False)
 
     Returns:
     The list of files in their destination.
     """
     files = walk_if(".", pred)
-    files = copy_to(files, root)
+    files = copy_to(files, root, rename_c_to_cpp)
     return files