diff --git a/build_tests/helloworld.cc b/build_tests/helloworld.cc
index c034e96..f12349e 100644
--- a/build_tests/helloworld.cc
+++ b/build_tests/helloworld.cc
@@ -1,5 +1,3 @@
-#include <stdio.h>
+#include <cstdio>
 
-int main() {
-  printf("Hello, World!\n");
-}
+int main() { printf("Hello, World!\n"); }
diff --git a/build_tests/tcmalloc.cc b/build_tests/tcmalloc.cc
index 7fb9105..bc5f03e 100644
--- a/build_tests/tcmalloc.cc
+++ b/build_tests/tcmalloc.cc
@@ -1,6 +1,7 @@
-#include <stdlib.h>
 #include <unistd.h>
 
+#include <cstdlib>
+
 int main() {
   void *big_chunk = malloc(500000 + read(-1, nullptr, 0));
   if (write(-1, big_chunk, 0) != -1) return 1;