diff --git a/source/tests/CarlaUtils.cpp b/source/tests/CarlaUtils.cpp
index ba1b72f11..4dfa59990 100644
--- a/source/tests/CarlaUtils.cpp
+++ b/source/tests/CarlaUtils.cpp
@@ -36,7 +36,7 @@
 #include "CarlaLv2Utils.hpp"
 #include "CarlaVstUtils.hpp"
 
-#include "CarlaLibUtils.hpp"
+#include "CarlaLibCounter.hpp"
 #include "CarlaShmUtils.hpp"
 
 // used in dssi utils
@@ -622,6 +622,31 @@ static void test_CarlaLibUtils() noexcept
 
     const bool closed = lib_close(lib);
     CARLA_SAFE_ASSERT(closed);
+
+    LibCounter lc;
+    void* const test1 = lc.open("/usr/lib/liblo.so");
+    void* const test2 = lc.open("/usr/lib/liblo.so");
+    void* const test3 = lc.open("/usr/lib/liblo.so");
+    assert(test1 == test2);
+    assert(test2 == test3);
+    lc.close(test1); lc.close(test2); lc.close(test3);
+
+    // test if the pointer changes after all closed
+    void* const test1b = lc.open("/usr/lib/liblo.so");
+    assert(test1 != test1b);
+    lc.close(test1b);
+
+    // test non-delete flag
+    void* const test4 = lc.open("/usr/lib/liblrdf.so.0", false);
+    lc.close(test4);
+    void* const test5 = lc.open("/usr/lib/liblrdf.so.0");
+    assert(test4 == test5);
+    lc.close(test5);
+
+    // open non-delete a few times, tests for cleanup on destruction
+    lc.open("/usr/lib/liblrdf.so.0");
+    lc.open("/usr/lib/liblrdf.so.0");
+    lc.open("/usr/lib/liblrdf.so.0");
 }
 
 #if 0
diff --git a/source/utils/CarlaLibCounter.hpp b/source/utils/CarlaLibCounter.hpp
index 7bdd21923..50721d500 100644
--- a/source/utils/CarlaLibCounter.hpp
+++ b/source/utils/CarlaLibCounter.hpp
@@ -38,6 +38,9 @@ public:
             CARLA_SAFE_ASSERT_CONTINUE(lib.count > 0);
             CARLA_SAFE_ASSERT_CONTINUE(lib.lib != nullptr);
 
+            // all libs should be closed by now except those explicitly marked non-delete
+            CARLA_SAFE_ASSERT(! lib.canDelete);
+
             if (! lib_close(lib.lib))
                 carla_stderr("LibCounter cleanup failed, reason:\n%s", lib_error(lib.filename));
 
@@ -65,7 +68,7 @@ public:
         }
         CARLA_SAFE_EXCEPTION_RETURN("LibCounter::open", nullptr);
 
-        const CarlaMutexLocker sl(fMutex);
+        const CarlaMutexLocker cml(fMutex);
 
         for (LinkedList<Lib>::Itenerator it = fLibs.begin(); it.valid(); it.next())
         {
@@ -75,6 +78,9 @@ public:
 
             if (std::strcmp(lib.filename, filename) == 0)
             {
+                // will not be needed
+                delete[] dfilename;
+
                 ++lib.count;
                 return lib.lib;
             }
@@ -105,7 +111,7 @@ public:
     {
         CARLA_SAFE_ASSERT_RETURN(libPtr != nullptr, false);
 
-        const CarlaMutexLocker sl(fMutex);
+        const CarlaMutexLocker cml(fMutex);
 
         for (LinkedList<Lib>::Itenerator it = fLibs.begin(); it.valid(); it.next())
         {