diff --git a/project.gyp b/project.gyp
index 7ae20e54..ffceb80b 100644
--- a/project.gyp
+++ b/project.gyp
@@ -136,8 +136,8 @@
         },
       },
       'Fuzz': {
-        'cflags': [ '-g', '-fsanitize=address,undefined', '-fsanitize-coverage=trace-pc-guard' ],
-        'ldflags': [ '-g', '-fsanitize=address,undefined', '-fsanitize-coverage=trace-pc-guard' ],
+        'cflags': ['<!@(echo $CFLAGS)'],
+        'ldflags': ['<!@(echo $CXXFLAGS)'],
       },
       'Release': {
         'cflags': [ '-O2', '-fno-strict-aliasing' ],
diff --git a/script/build-fuzzers b/script/build-fuzzers
index 8e8de5a6..d4786daf 100755
--- a/script/build-fuzzers
+++ b/script/build-fuzzers
@@ -15,13 +15,16 @@ CC=${CC:-clang}
 CXX=${CXX:-clang++}
 LINK=${LINK:-clang++}
 
-CC=$CC CXX=$CXX LINK=$LINK ./script/configure
+default_fuzz_flags="-fsanitize=address,undefined -fsanitize-coverage=trace-pc-guard"
+
+CFLAGS=${CFLAGS:-"$default_fuzz_flags"}
+CXXFLAGS=${CXXFLAGS:-"$default_fuzz_flags"}
+
+CC=$CC CXX=$CXX LINK=$LINK CFLAGS=$CFLAGS CXXFLAGS=$CXXFLAGS ./script/configure
 
 export BUILDTYPE=Fuzz
 make runtime
 
-CFLAGS="-fsanitize=address,undefined -fsanitize-coverage=trace-pc-guard"
-CXXFLAGS="-fsanitize=address,undefined -fsanitize-coverage=trace-pc-guard"
 
 if [ -z "$@" ]; then
   languages=$(ls test/fixtures/grammars)