diff --git a/contrib/devtools/build_cmake.sh b/contrib/devtools/build_cmake.sh
index 7bb262ac7..cbb28d823 100755
--- a/contrib/devtools/build_cmake.sh
+++ b/contrib/devtools/build_cmake.sh
@@ -1,46 +1,49 @@
 #!/usr/bin/env bash
 
 export LC_ALL=C
 
 set -euxo pipefail
 
 : "${TOPLEVEL:=$(git rev-parse --show-toplevel)}"
 : "${BUILD_DIR:=${TOPLEVEL}/build}"
 
 function usage() {
   echo "Usage: $0 [--Werror]"
   echo "Build the default target using cmake and ninja."
   echo "Options:"
   echo "  --Werror: add -Werror to the compiler flags"
   echo "Environment variables:"
   echo "  CMAKE_FLAGS: array of the CMAKE flags to use for the build"
   echo "  BUILD_DIR: the build directory, (default: ${BUILD_DIR}})"
   echo "  TOPLEVEL: the project root directory, (default: ${TOPLEVEL}})"
 }
 
 # Default to nothing
 : "${CMAKE_FLAGS:=}"
 
 mkdir -p "${BUILD_DIR}"
 cd ${BUILD_DIR}
 git clean -xffd
 
 read -a CMAKE_FLAGS <<< "${CMAKE_FLAGS}"
 
-case "$1" in
-  "--Werror")
-    CMAKE_FLAGS+=(
-      "-DCMAKE_C_FLAGS=-Werror"
-      "-DCMAKE_CXX_FLAGS=-Werror"
-    )
-    ;;
-  *)
-    usage
-    exit 1
-    ;;
-esac
+while [[ $# -gt 0 ]]; do
+  case $1 in
+    --Werror)
+      CMAKE_FLAGS+=(
+        "-DCMAKE_C_FLAGS=-Werror"
+        "-DCMAKE_CXX_FLAGS=-Werror"
+      )
+      shift
+      ;;
+    *)
+      usage
+      exit 1
+      ;;
+  esac
+done
 
 cmake -GNinja .. "${CMAKE_FLAGS[@]}"
 
 # Run build
 ninja