diff --git a/Cargo.lock b/Cargo.lock
index cebdf483816..b43b2c3b1a6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2068,9 +2068,9 @@ checksum = "9b919933a397b79c37e33b77bb2aa3dc8eb6e165ad809e58ff75bc7db2e34574"
 
 [[package]]
 name = "glslopt"
-version = "0.1.2"
+version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f22b383fcf6f85c4a268af39a0758ec40970e5f9f8fe9809e4415d48409b8379"
+checksum = "065c2e941ad25c18428724fd2ad0bc3967cb96242e8db92f3794eedb15c02e44"
 dependencies = [
  "cc",
 ]
diff --git a/python/servo/build_commands.py b/python/servo/build_commands.py
index 58654be2dfd..9c2e7429463 100644
--- a/python/servo/build_commands.py
+++ b/python/servo/build_commands.py
@@ -655,10 +655,10 @@ class MachCommands(CommandBase):
             env.setdefault("CC", "clang-cl.exe")
             env.setdefault("CXX", "clang-cl.exe")
             if uwp:
-                env.setdefault("CFLAGS", "")
-                env.setdefault("CXXFLAGS", "")
-                env["CFLAGS"] += " -DWINAPI_FAMILY=WINAPI_FAMILY_APP"
-                env["CXXFLAGS"] += " -DWINAPI_FAMILY=WINAPI_FAMILY_APP"
+                env.setdefault("TARGET_CFLAGS", "")
+                env.setdefault("TARGET_CXXFLAGS", "")
+                env["TARGET_CFLAGS"] += " -DWINAPI_FAMILY=WINAPI_FAMILY_APP"
+                env["TARGET_CXXFLAGS"] += " -DWINAPI_FAMILY=WINAPI_FAMILY_APP"
         else:
             env.setdefault("CC", "clang")
             env.setdefault("CXX", "clang++")