diff --git a/.drone.yml b/.drone.yml
index cd0ad45..4a66a99 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -38,7 +38,7 @@ name: tag
 
 steps:
   - name: Build release
-    image: registry.riba-interactive.de/alpine-build:3
+    image: registry.riba-interactive.de/alpine-build:4
     commands:
       - cmake -S. -Bcmake-build-ci -DCMAKE_BUILD_TYPE=Release
       - cd cmake-build-ci
@@ -58,7 +58,7 @@ name: Build and Test
 
 steps:
   - name: Build and run tests
-    image: registry.riba-interactive.de/alpine-build:3
+    image: registry.riba-interactive.de/alpine-build:4
     commands:
       - cmake -S. -Bcmake-build-ci -DCMAKE_BUILD_TYPE=Debug -DENABLE_TEST_COVERAGE=on
       - cd cmake-build-ci
diff --git a/CMakeLists.txt b/CMakeLists.txt
index bdd63ad..2656f6c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -35,7 +35,7 @@ if ((CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME OR MODERN_CMAKE_BUILD_TESTING)
 
         setup_target_for_coverage_lcov(
                 NAME coverage
-                EXECUTABLE ${CMAKE_CTEST_COMMAND}
+                EXECUTABLE ${CMAKE_CTEST_COMMAND} -T memcheck
                 EXCLUDE "tests/*"
                 LCOV_ARGS --rc lcov_branch_coverage=1
                 GENHTML_ARGS --rc genhtml_branch_coverage=1
diff --git a/build/Dockerfile.build b/build/Dockerfile.build
index 006e6ac..5df567a 100644
--- a/build/Dockerfile.build
+++ b/build/Dockerfile.build
@@ -8,4 +8,5 @@ RUN echo "@testing https://dl-cdn.alpinelinux.org/alpine/edge/testing" >> /etc/a
     flex \
     git \
     ncurses-dev\
-    lcov@testing
\ No newline at end of file
+    lcov@testing \
+    valgrind
\ No newline at end of file
diff --git a/tests/library/hashtable/test_hashtable.c b/tests/library/hashtable/test_hashtable.c
index 7479cc0..0bd3047 100644
--- a/tests/library/hashtable/test_hashtable.c
+++ b/tests/library/hashtable/test_hashtable.c
@@ -109,12 +109,18 @@ spec("hashtable") {
 
             it("should not work with the str having NULL as string") {
                 str key = STR_NULL_INIT;
-                check(value_hashtable_insert(hashtable, key, value_new(1337)) == 0);
+                value *value = value_new(1337);
+                check(value_hashtable_insert(hashtable, key, value) == 0);
+                check(value != NULL, "value should not be NULL");
+                value_destroy(&value);
             }
 
             it("should return 0 with NULL as this param") {
                 str key = STR_STATIC_INIT("leet");
-                check(value_hashtable_insert(NULL, key, value_new(1)) == 0, "return should be 0");
+                value *value = value_new(1);
+                check(value_hashtable_insert(NULL, key, value) == 0, "return should be 0");
+                check(value != NULL, "value should not be NULL");
+                value_destroy(&value);
             }
 
             it("should not allow double entry") {
@@ -124,7 +130,10 @@ spec("hashtable") {
                 check(value_hashtable_insert(hashtable, key, value_new(1337)) == 1);
                 check(value_hashtable_has(hashtable, key) == 1, "hashtable should have the key");
 
-                check(value_hashtable_insert(hashtable, key, value_new(1337)) == 0);
+                value *value = value_new(1337);
+                check(value_hashtable_insert(hashtable, key, value) == 0, "return should be 0");
+                check(value != NULL, "value should not be NULL");
+                value_destroy(&value);
             }
         }
 
@@ -167,7 +176,6 @@ spec("hashtable") {
                 check(value_hashtable_markStolenCheck(hashtable, key, (value_hashtable_value_check_fn) value_check_counter, &counter) == 1);
                 check(value_hashtable_isStolenCheck(hashtable, key, (value_hashtable_value_check_fn) value_check_counter, &counter) == 1);
                 value_destroy(&resultValue);
-                check(resultValue == NULL, "resultValue should be NULL");
             }
         }
 
@@ -206,12 +214,15 @@ spec("hashtable") {
         describe("value_hashtable_markStolen()") {
             it("should mark the value for the given key as stolen") {
                 str key = STR_STATIC_INIT("leet");
-
+                value *value = NULL;
                 check(value_hashtable_has(hashtable, key) == 0,"hashtable should not have the key already");
                 check(value_hashtable_insert(hashtable, key, value_new(1337)) == 1);
                 check(value_hashtable_has(hashtable, key) == 1, "hashtable should have the key");
+                value = value_hashtable_lookup(hashtable, key);
+                check(value != NULL, "value should not be NULL");
                 check(value_hashtable_markStolen(hashtable, key) == 1, "hashtable should mark the value for the key as stolen");
                 check(value_hashtable_isStolen(hashtable, key) == 1, "hashtable should have the value for the key marked as stolen");
+                value_destroy(&value);
             }
 
             it("should return 0 the given key that is not existing") {
@@ -224,8 +235,12 @@ spec("hashtable") {
 
             it("should work with the empty str") {
                 str key = STR_STATIC_INIT("");
+                value *value = NULL;
                 check(value_hashtable_insert(hashtable, key, value_new(1337)) == 1);
+                value = value_hashtable_lookup(hashtable, key);
+                check(value != NULL, "value should not be NULL");
                 check(value_hashtable_markStolen(hashtable, key) == 1, "return should be 1");
+                value_destroy(&value);
             }
 
             it("should not work with the str having NULL as string") {
@@ -303,6 +318,7 @@ spec("hashtable") {
                 str otherKey2 = STR_STATIC_INIT("otherKey2");
                 str otherKey3 = STR_STATIC_INIT("otherKey3");
                 str otherKey4 = STR_STATIC_INIT("otherKey4");
+                value *value = NULL;
 
                 check(value_hashtable_has(hashtable, key) == 0,"hashtable should not have the key already");
                 check(value_hashtable_insert(hashtable, key, value_new(1337)) == 1);
@@ -313,8 +329,11 @@ spec("hashtable") {
                 check(value_hashtable_insert(hashtable, otherKey3, value_new(1337)) == 1);
                 check(value_hashtable_insert(hashtable, otherKey4, value_new(1337)) == 1);
 
+                value = value_hashtable_lookup(hashtable, key);
+                check(value != NULL, "value should not be NULL");
                 check(value_hashtable_markStolen(hashtable, key) == 1, "hashtable should mark the value for the key as stolen");
                 check(value_hashtable_isStolen(hashtable, key) == 1, "hashtable should have the value for the key marked as stolen");
+                value_destroy(&value);
             }
         }
     }
diff --git a/tests/library/list/test_list.c b/tests/library/list/test_list.c
index faa9aea..e63718d 100644
--- a/tests/library/list/test_list.c
+++ b/tests/library/list/test_list.c
@@ -78,7 +78,10 @@ spec("list") {
             for_it_end();
 
             it("should return 0 with NULL as this param") {
-                check(value_list_push(NULL, value_new(1)) == 0, "return should not be 0");
+                value *value = value_new(1);
+                check(value_list_push(NULL, value) == 0, "return should not be 0");
+                check(value != NULL, "value should not be NULL");
+                value_destroy(&value);
             }
 
             it("should return 0 with NULL as valueElement param") {
@@ -130,7 +133,9 @@ spec("list") {
             for_it_end();
 
             it("should return 0 with NULL as this param") {
-                check(value_list_unshift(NULL, value_new(1)) == 0, "return should not be 0");
+                value *value = value_new(1);
+                check(value_list_unshift(NULL, value) == 0, "return should not be 0");
+                value_destroy(&value);
             }
 
             it("should return 0 with NULL as valueElement param") {