diff --git a/src/collocatordb.cc b/src/collocatordb.cc
index e2d37d5..28035f6 100644
--- a/src/collocatordb.cc
+++ b/src/collocatordb.cc
@@ -1,15 +1,15 @@
 #define EXPORT __attribute__((visibility("visible")))
 #define IMPORT
 
-#include <assert.h>
+#include <cassert>
 #include <memory>
 #include <iostream>
 #include <algorithm>
 #include <vector>
-#include <stdint.h>
+#include <cstdint>
 #include <string>
 #include <sstream> // for ostringstream
-#include <math.h>
+#include <cmath>
 #include <rocksdb/cache.h>
 #include "rocksdb/db.h"
 #include "rocksdb/env.h"
diff --git a/tests/basic_test.c b/tests/basic_test.c
index 780a434..eb0471d 100644
--- a/tests/basic_test.c
+++ b/tests/basic_test.c
@@ -9,16 +9,12 @@
 const int testword = 10; // ist
 
 void test_open_db() {
-  COLLOCATORDB *cdb;
-
-  cdb = open_collocatordb(dbpath);
+  COLLOCATORDB* cdb = open_collocatordb(dbpath);
   TEST_ASSERT(cdb != NULL);
 }
 
 void test_get_word() {
-  COLLOCATORDB *cdb;
-
-  cdb = open_collocatordb(dbpath);
+  COLLOCATORDB* cdb = open_collocatordb(dbpath);
   TEST_ASSERT(cdb != NULL);
   char *word = get_word(cdb, testword);
   char *expected = "ist";
@@ -28,9 +24,7 @@
 }
 
 void test_collocation_scores() {
-  COLLOCATORDB *cdb;
-
-  cdb = open_collocatordb(dbpath);
+  COLLOCATORDB* cdb = open_collocatordb(dbpath);
   TEST_ASSERT(cdb != NULL);
   char *expected = " { \"f1\": 217,\"w1\":\"Aluminium\", \"N\": 152743, \"collocates\": [{\"word\":\"Anwendungstechnologie\",\"f2\":16,\"f\":16,\"npmi\":0.594849,\"pmi\":8.4592,\"llr\":188.227,\"lfmd\":16.4592,\"md\":12.4592,\"dice\":0.0711111,\"ld\":10.1862,\"ln_count\":16,\"rn_count\":0,\"ln_pmi\":9.4592,\"rn_pmi\":-1,\"ldaf\":11.1358,\"win\":32,\"afwin\":32}]}\n";
   char *produced = get_collocation_scores_as_json(cdb, 62, 966);
@@ -41,9 +35,7 @@
 
 
 void test_collocation_analysis_as_json() {
-  COLLOCATORDB *cdb;
-
-  cdb = open_collocatordb(dbpath);
+  COLLOCATORDB* cdb = open_collocatordb(dbpath);
   TEST_ASSERT(cdb != NULL);
   char *json = get_collocators_as_json(cdb, testword);
   char *needle = "\"word\":\"um\",\"f2\":264,\"f\":5,\"npmi\":-0.0556349,\"pmi\":-0.958074,\"llr\":2.87723,\"lfmd\":3.68578,\"md\":1.36385,\"dice\":0.00169952,\"ld\":4.79935,\"ln_count\":0,\"rn_count\":1,\"ln_pmi\":-1,\"rn_pmi\":-1,\"ldaf\":4.79935,\"win\":668,\"afwin\":668";
@@ -52,9 +44,7 @@
 }
 
 void test_collocation_analysis() {
-  COLLOCATORDB *cdb;
-
-  cdb = open_collocatordb(dbpath);
+  COLLOCATORDB* cdb = open_collocatordb(dbpath);
   TEST_ASSERT(cdb != NULL);
   char *expected = "Anwendungstechnologie";
   const COLLOCATOR *c = get_collocators(cdb, 62);