diff --git a/.github/workflows/build.sh b/.github/workflows/build.sh
index 0d4afab3..5dfa741e 100755
--- a/.github/workflows/build.sh
+++ b/.github/workflows/build.sh
@@ -17,6 +17,7 @@ fi
 
 export CC=$GH_COMPILER
 export CXX=${CC%cc}++
+export CXXFLAGS_EARLY=-Werror
 
 if [[ "$GH_BUILDSYS" == "makefile" ]]; then
   make
diff --git a/.travis.yml b/.travis.yml
index 95516a05..6c8e9887 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -162,6 +162,7 @@ script:
   fi
 - |-
   # Build hyperrogue.
+  export CXXFLAGS_EARLY=-Werror
   if [[ "$TRAVIS_BUILD_SYSTEM" == "Makefile" ]]; then
     make
   elif [[ "$TRAVIS_BUILD_SYSTEM" == "mymake" ]]; then
diff --git a/Makefile b/Makefile
index 004eb426..f37f5bde 100644
--- a/Makefile
+++ b/Makefile
@@ -81,24 +81,23 @@ endif
 
 ifeq (${TOOLCHAIN},clang)
   CXXFLAGS_STD = -std=c++11
-  CXXFLAGS_EARLY += -march=native -fPIC
-  CXXFLAGS_EARLY += -W -Wall -Wextra -Wsuggest-override -Werror -pedantic
+  CXXFLAGS_EARLY += -fPIC
+  CXXFLAGS_EARLY += -W -Wall -Wextra -Wsuggest-override -pedantic
   CXXFLAGS_EARLY += -Wno-unused-parameter -Wno-implicit-fallthrough -Wno-maybe-uninitialized -Wno-unknown-warning-option
   CXXFLAGS_EARLY += -Wno-invalid-offsetof
 endif
 
 ifeq (${TOOLCHAIN},gcc)
   CXXFLAGS_STD = -std=c++11
-  CXXFLAGS_EARLY += -march=native -fPIC
-  CXXFLAGS_EARLY += -W -Wall -Wextra -Werror -pedantic
+  CXXFLAGS_EARLY += -fPIC
+  CXXFLAGS_EARLY += -W -Wall -Wextra -pedantic
   CXXFLAGS_EARLY += -Wno-unused-parameter -Wno-implicit-fallthrough -Wno-maybe-uninitialized
   CXXFLAGS_EARLY += -Wno-invalid-offsetof
 endif
 
 ifeq (${TOOLCHAIN},mingw)
   CXXFLAGS_STD = -std=c++11
-  CXXFLAGS_EARLY += -march=native
-  CXXFLAGS_EARLY += -W -Wall -Wextra -Werror
+  CXXFLAGS_EARLY += -W -Wall -Wextra
   CXXFLAGS_EARLY += -Wno-unused-parameter -Wno-implicit-fallthrough -Wno-maybe-uninitialized
   CXXFLAGS_EARLY += -Wno-invalid-offsetof
 endif