diff --git a/third-party/webp/build-webp-bazel.sh b/third-party/webp/build-webp-bazel.sh
index ce0e395b6b..c199cba8f1 100755
--- a/third-party/webp/build-webp-bazel.sh
+++ b/third-party/webp/build-webp-bazel.sh
@@ -42,7 +42,7 @@ SDKROOT="$(xcrun --sdk $PLATFORM --show-sdk-path 2>/dev/null)"
 DEVROOT="${DEVELOPER}/Toolchains/XcodeDefault.xctoolchain"
 
 CFLAGS="-pipe -isysroot ${SDKROOT} -O3 -DNDEBUG $EXTRA_CFLAGS"
-CFLAGS+="-miphoneos-version-min=9.0"
+CFLAGS+=" -miphoneos-version-min=9.0"
 
 PATH="${DEVROOT}/usr/bin:${PATH}" ./configure \
   ${EXTRA_CONFIG} \