diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ea3185d2a1..1aa0906ffc 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -119,6 +119,10 @@ jobs:
             cc: clang-13
             runner: ubuntu-20.04
             os: linux
+          - flavor: uchar
+            cc: gcc
+            runner: ubuntu-20.04
+            os: linux
           - cc: clang
             runner: macos-10.15
             os: osx
diff --git a/.github/workflows/env.sh b/.github/workflows/env.sh
index bd170f92fb..ca1194efa9 100755
--- a/.github/workflows/env.sh
+++ b/.github/workflows/env.sh
@@ -43,6 +43,11 @@ EOF
     cat <<EOF >> "$GITHUB_ENV"
 TSAN_OPTIONS=log_path=$GITHUB_WORKSPACE/build/log/tsan
 CLANG_SANITIZER=TSAN
+EOF
+    ;;
+  uchar)
+    cat <<EOF >> "$GITHUB_ENV"
+BUILD_UCHAR=1
 EOF
     ;;
   lint)
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 82d9a42db2..01df172ed4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -370,7 +370,7 @@ option(CI_BUILD "CI, extra flags will be set" OFF)
 if(CI_BUILD)
   message(STATUS "CI build enabled")
   add_compile_options(-Werror)
-  if(DEFINED ENV{BUILD_32BIT})
+  if(DEFINED ENV{BUILD_UCHAR})
     # Get some test coverage for unsigned char
     add_compile_options(-funsigned-char)
   endif()