diff --git a/repos/libports/src/lib/libc/malloc.cc b/repos/libports/src/lib/libc/malloc.cc
index 923ba1a876..f6901275b2 100644
--- a/repos/libports/src/lib/libc/malloc.cc
+++ b/repos/libports/src/lib/libc/malloc.cc
@@ -192,7 +192,8 @@ extern "C" void *malloc(size_t size)
 extern "C" void *calloc(size_t nmemb, size_t size)
 {
 	void *addr = malloc(nmemb*size);
-	Genode::memset(addr, 0, nmemb*size);
+	if (addr)
+		Genode::memset(addr, 0, nmemb*size);
 	return addr;
 }