diff --git a/.travis.yml b/.travis.yml
index c5ccd563..749e4e24 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,11 +20,7 @@ before_install:
 matrix:
   include:
     - compiler: clang
-      env: CUSTOM_ALLOC=ON
-    - compiler: clang
-      env: CUSTOM_ALLOC=OFF
     - compiler: gcc
-      env: CUSTOM_ALLOC=OFF
 
 script:
   - export SOURCE=$(pwd) && ./buildscript.sh
diff --git a/buildscript.sh b/buildscript.sh
index 7ddc5172..b4f29aa0 100755
--- a/buildscript.sh
+++ b/buildscript.sh
@@ -6,7 +6,7 @@ cd $SOURCE
 cppcheck . --error-exitcode=1 --suppressions cppcheck_suppressions.txt --force
 cd $PREVD
 
-cmake $SOURCE -DCUSTOM_ALLOC=$CUSTOM_ALLOC -DCMAKE_BUILD_TYPE=Debug
+cmake $SOURCE -DCUSTOM_ALLOC=ON -DCMAKE_BUILD_TYPE=Debug
 make VERBOSE=1
 ctest -V
 
diff --git a/test/fuzz_test.c b/test/fuzz_test.c
index 60494379..1a2c8610 100644
--- a/test/fuzz_test.c
+++ b/test/fuzz_test.c
@@ -38,6 +38,16 @@ static void printmem(const unsigned char * ptr, size_t length)
 
 unsigned seed;
 
+#ifdef CBOR_CUSTOM_ALLOC
+void *mock_malloc(size_t size)
+{
+	if (size > (1 << 19))
+		return NULL;
+	else
+		return malloc(size);
+}
+#endif
+
 static void run_round()
 {
 	cbor_item_t *item;
@@ -64,6 +74,10 @@ static void run_round()
 
 static void fuzz(void **state)
 {
+
+#ifdef CBOR_CUSTOM_ALLOC
+	cbor_set_allocs(mock_malloc, realloc, free);
+#endif
 	printf(
 		"Fuzzing %llu rounds of up to %llu bytes with seed %u\n",
 		ROUNDS,