diff --git a/.github/workflows/ci-disable-gtest.yml b/.github/workflows/ci-disable-gtest.yml
index 09938b104c..c07974a721 100644
--- a/.github/workflows/ci-disable-gtest.yml
+++ b/.github/workflows/ci-disable-gtest.yml
@@ -95,6 +95,7 @@ jobs:
         -DAVIF_LIBYUV=LOCAL -DAVIF_LIBSHARPYUV=LOCAL
         -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
         -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=OFF
+        -DAVIF_ENABLE_WERROR=ON
     - name: Build libavif (ninja)
       working-directory: ./build
       run: ninja
diff --git a/.github/workflows/ci-linux-golden-tests.yml b/.github/workflows/ci-linux-golden-tests.yml
index 5c8a304df6..2a5a0b5b1b 100644
--- a/.github/workflows/ci-linux-golden-tests.yml
+++ b/.github/workflows/ci-linux-golden-tests.yml
@@ -78,7 +78,7 @@ jobs:
         -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
         -DAVIF_LOCAL_LIBXML2=ON
         -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GOLDEN_TESTS=ON
-        -DAVIF_ENABLE_GTEST=OFF
+        -DAVIF_ENABLE_GTEST=OFF -DAVIF_ENABLE_WERROR=ON
         -DGOLDEN_TESTS_OUTPUT_DIR=${{ runner.temp }}/golden_tests
     - name: Build libavif (ninja)
       working-directory: ./build
diff --git a/.github/workflows/ci-mingw.yml b/.github/workflows/ci-mingw.yml
index 869e663f7c..bd52b26b19 100644
--- a/.github/workflows/ci-mingw.yml
+++ b/.github/workflows/ci-mingw.yml
@@ -76,6 +76,7 @@ jobs:
         -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
         -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_LOCAL_GTEST=ON
         -DAVIF_BUILD_GDK_PIXBUF=ON -DCMAKE_INSTALL_PREFIX=./install
+        -DAVIF_ENABLE_WERROR=ON
     - name: Build libavif (ninja)
       working-directory: ./build
       run: ninja
diff --git a/.github/workflows/ci-unix-shared-installed.yml b/.github/workflows/ci-unix-shared-installed.yml
index adc5f95a9f..8f05f95072 100644
--- a/.github/workflows/ci-unix-shared-installed.yml
+++ b/.github/workflows/ci-unix-shared-installed.yml
@@ -76,6 +76,7 @@ jobs:
         -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
         -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_LOCAL_GTEST=ON
         -DAVIF_BUILD_GDK_PIXBUF=ON -DCMAKE_INSTALL_PREFIX=./install
+        -DAVIF_ENABLE_WERROR=ON
     - name: Build libavif (ninja)
       working-directory: ./build
       run: ninja
diff --git a/.github/workflows/ci-unix-shared-local.yml b/.github/workflows/ci-unix-shared-local.yml
index 6166ed2785..2317e2b7d9 100644
--- a/.github/workflows/ci-unix-shared-local.yml
+++ b/.github/workflows/ci-unix-shared-local.yml
@@ -90,6 +90,7 @@ jobs:
         -DAVIF_LIBSHARPYUV=LOCAL
         -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
         -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_LOCAL_GTEST=ON
+        -DAVIF_ENABLE_WERROR=ON
     - name: Build libavif (ninja)
       working-directory: ./build
       run: ninja
diff --git a/.github/workflows/ci-unix-static-av2.yml b/.github/workflows/ci-unix-static-av2.yml
index 9ce329a567..6e3ecea5ab 100644
--- a/.github/workflows/ci-unix-static-av2.yml
+++ b/.github/workflows/ci-unix-static-av2.yml
@@ -97,6 +97,7 @@ jobs:
         -DAVIF_LIBSHARPYUV=LOCAL
         -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
         -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_LOCAL_GTEST=ON
+        -DAVIF_ENABLE_WERROR=ON
     - name: Build libavif (ninja)
       working-directory: ./build
       run: ninja
diff --git a/.github/workflows/ci-unix-static.yml b/.github/workflows/ci-unix-static.yml
index 1e074c0e50..65f08a8bce 100644
--- a/.github/workflows/ci-unix-static.yml
+++ b/.github/workflows/ci-unix-static.yml
@@ -109,6 +109,7 @@ jobs:
         -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
         -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
         -DAVIF_ENABLE_EXPERIMENTAL_AVIR=ON
+        -DAVIF_ENABLE_WERROR=ON
     - name: Build libavif (ninja)
       working-directory: ./build
       run: ninja
diff --git a/.github/workflows/ci-windows-artifacts.yml b/.github/workflows/ci-windows-artifacts.yml
index fc9304cf4d..3669085874 100644
--- a/.github/workflows/ci-windows-artifacts.yml
+++ b/.github/workflows/ci-windows-artifacts.yml
@@ -82,7 +82,7 @@ jobs:
         -DAVIF_LIBYUV=LOCAL -DAVIF_LOCAL_JPEG=ON
         -DAVIF_LIBSHARPYUV=LOCAL -DAVIF_LOCAL_ZLIBPNG=ON
         -DAVIF_BUILD_EXAMPLES=OFF -DAVIF_BUILD_APPS=ON
-        -DAVIF_BUILD_TESTS=OFF
+        -DAVIF_BUILD_TESTS=OFF -DAVIF_ENABLE_WERROR=ON
     - name: Build libavif (ninja)
       working-directory: ./build
       run: ninja
diff --git a/.github/workflows/ci-windows.yml b/.github/workflows/ci-windows.yml
index 2b08050c47..dd9f684f00 100644
--- a/.github/workflows/ci-windows.yml
+++ b/.github/workflows/ci-windows.yml
@@ -114,7 +114,7 @@ jobs:
         -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_LOCAL_GTEST=ON
         -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
         -DAVIF_ENABLE_EXPERIMENTAL_GAIN_MAP=ON
-        -DAVIF_ENABLE_EXPERIMENTAL_AVIR=ON
+        -DAVIF_ENABLE_EXPERIMENTAL_AVIR=ON -DAVIF_ENABLE_WERROR=ON
     - name: Build libavif (ninja)
       working-directory: ./build
       run: ninja
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5bc424b50f..f4f7268c35 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -74,6 +74,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * For the libyuv, libsharpyuv, zlibpng and jpeg dependencies, AVIF_LOCAL_* is
   now replaced by flags AVIF_* that can take the values: OFF, LOCAL or SYSTEM.
 * src/reformat.c: Allocate the threadData array directly.
+* AVIF_ENABLE_WERROR is set to OFF by default.
 
 ## [1.0.3] - 2023-12-03
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 41d96921b6..9e41df1c66 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -34,7 +34,7 @@ set(LIBRARY_SOVERSION ${LIBRARY_VERSION_MAJOR})
 
 option(BUILD_SHARED_LIBS "Build shared avif library" ON)
 
-option(AVIF_ENABLE_WERROR "Treat all compiler warnings as errors" ON)
+option(AVIF_ENABLE_WERROR "Treat all compiler warnings as errors" OFF)
 option(AVIF_ENABLE_WUNUSED_RESULT "Add [[nodiscard]] to some functions. CMake must be at least 3.21 to force C23" OFF)
 
 option(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R "Enable experimental YCgCo-R matrix code" OFF)
diff --git a/appveyor.yml b/appveyor.yml
index 0aa90b6d91..1d1c6b6285 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -31,7 +31,7 @@ install:
  - mkdir build
  - cd build
  - cmake --version
- - cmake .. -DAVIF_CODEC_AOM=LOCAL -DAVIF_CODEC_DAV1D=LOCAL  -DBUILD_SHARED_LIBS=OFF -DAVIF_LOCAL_JPEG=ON -DAVIF_LOCAL_ZLIBPNG=ON -DAVIF_LIBYUV=LOCAL -DAVIF_BUILD_APPS=ON
+ - cmake .. -DAVIF_CODEC_AOM=LOCAL -DAVIF_CODEC_DAV1D=LOCAL  -DBUILD_SHARED_LIBS=OFF -DAVIF_LOCAL_JPEG=ON -DAVIF_LOCAL_ZLIBPNG=ON -DAVIF_LIBYUV=LOCAL -DAVIF_BUILD_APPS=ON -DAVIF_ENABLE_WERROR=ON
 
 build:
   project: build/libavif.sln
diff --git a/tests/docker/build.sh b/tests/docker/build.sh
index 6e518023cd..066fb579eb 100644
--- a/tests/docker/build.sh
+++ b/tests/docker/build.sh
@@ -71,7 +71,7 @@ git clone --depth 1 https://github.com/AOMediaCodec/libavif.git
 cd libavif
 mkdir build
 cd build
-cmake -G Ninja -DCMAKE_INSTALL_PREFIX=/usr -DAVIF_CODEC_AOM=1 -DAVIF_CODEC_DAV1D=1 -DAVIF_CODEC_LIBGAV1=1 -DAVIF_CODEC_RAV1E=1 -DAVIF_CODEC_SVT=1 -DAVIF_BUILD_APPS=1 ..
+cmake -G Ninja -DCMAKE_INSTALL_PREFIX=/usr -DAVIF_CODEC_AOM=1 -DAVIF_CODEC_DAV1D=1 -DAVIF_CODEC_LIBGAV1=1 -DAVIF_CODEC_RAV1E=1 -DAVIF_CODEC_SVT=1 -DAVIF_BUILD_APPS=1 -DAVIF_ENABLE_WERROR=ON ..
 ninja install
 
 # If we made it here, show off the goods!
diff --git a/tests/oss-fuzz/build.sh b/tests/oss-fuzz/build.sh
index 87579e31e1..fc973bae13 100755
--- a/tests/oss-fuzz/build.sh
+++ b/tests/oss-fuzz/build.sh
@@ -56,7 +56,7 @@ cmake .. -G Ninja -DBUILD_SHARED_LIBS=OFF -DAVIF_CODEC_AOM=LOCAL -DAVIF_CODEC_DA
       -DAVIF_LOCAL_FUZZTEST=ON \
       -DAVIF_LOCAL_GTEST=OFF -DAVIF_LOCAL_JPEG=ON -DAVIF_LOCAL_LIBSHARPYUV=ON \
       -DAVIF_LIBYUV=LOCAL -DAVIF_LOCAL_ZLIBPNG=ON \
-      -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=OFF \
+      -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=OFF -DAVIF_ENABLE_WERROR=ON \
       ${EXTRA_CMAKE_FLAGS}
 
 ninja