diff --git a/src/protocol/CompressionHandler.cpp b/src/protocol/CompressionHandler.cpp
index 0b1f900..321296a 100644
--- a/src/protocol/CompressionHandler.cpp
+++ b/src/protocol/CompressionHandler.cpp
@@ -1,4 +1,3 @@
-#include <csignal>
 #include <misc/memtracker.h>
 #include "CompressionHandler.h"
 #define QLZ_COMPRESSION_LEVEL 1
@@ -39,17 +38,38 @@ namespace ts::compression {
             void* buffer_ptr{nullptr};
             size_t buffer_length{0};
     };
+
+    class qlz_states {
+        public:
+            qlz_states() noexcept {
+                this->state_compress = (qlz_state_compress*) malloc(sizeof(qlz_state_compress));
+                this->state_decompress = (qlz_state_decompress*) malloc(sizeof(qlz_state_decompress));
+            }
+
+            ~qlz_states() {
+                ::free(this->state_compress);
+                ::free(this->state_decompress);
+            }
+
+            qlz_state_compress* state_compress{nullptr};
+            qlz_state_decompress* state_decompress{nullptr};
+        private:
+    };
+
     thread_local thread_buffer qlz_buffer{};
+    thread_local qlz_states qlz_states{};
 
     size_t qlz_decompressed_size(const void* payload, size_t payload_length) {
+        if(payload_length < 9) return 0; /* payload too small */
+
         return qlz_size_decompressed((char*) payload) + 400;
     }
 
     bool qlz_decompress_payload(const void* payload, void* buffer, size_t* buffer_size) {
+        if(!qlz_states.state_decompress) return false;
         assert(payload != buffer);
 
-        qlz_state_decompress state{};
-        size_t data_length = qlz_decompress((char*) payload, (char*) buffer, &state);
+        size_t data_length = qlz_decompress((char*) payload, (char*) buffer, qlz_states.state_decompress);
         if(data_length <= 0)
             return false;
 
@@ -60,16 +80,18 @@ namespace ts::compression {
     }
 
     size_t qlz_compressed_size(const void* payload, size_t payload_length) {
+        assert(payload_length >= 9);
         //// "Always allocate size + 400 bytes for the destination buffer when compressing." <= http://www.quicklz.com/manual.html
         return max(min(payload_length * 2, (size_t) (payload_length + 400ULL)), (size_t) 24ULL); /* at least 12 bytes (QLZ header) */
     }
 
     bool qlz_compress_payload(const void* payload, size_t payload_length, void* buffer, size_t* buffer_length) {
+        if(!qlz_states.state_compress) return false;
+
         assert(payload != buffer);
         assert(*buffer_length >= qlz_compressed_size(payload, payload_length));
 
-        qlz_state_compress state{};
-        size_t compressed_length = qlz_compress(payload, (char*) buffer, payload_length, &state);
+        size_t compressed_length = qlz_compress(payload, (char*) buffer, payload_length, qlz_states.state_compress);
         if(compressed_length > *buffer_length) terminate();
 
         if(compressed_length <= 0)
@@ -99,6 +121,9 @@ bool CompressionHandler::decompress(protocol::BasicPacket* packet, std::string &
     if(expected_length > this->max_packet_size){ //Max 16MB. (97% Compression!)
         error = "Invalid packet size. (Calculated target length of " + to_string(expected_length) + ". Max length: " + to_string(this->max_packet_size) + ")";
         return false;
+    } else if(expected_length == 0) {
+        error = "Failed to calculate decompressed packet length";
+        return false;
     }
     auto header_length = packet->header().length() + packet->mac().length();
     auto buffer = buffer::allocate_buffer(expected_length + header_length);
diff --git a/src/protocol/CompressionHandler.h b/src/protocol/CompressionHandler.h
index b76d655..cd8c541 100644
--- a/src/protocol/CompressionHandler.h
+++ b/src/protocol/CompressionHandler.h
@@ -4,6 +4,7 @@
 
 namespace ts {
     namespace compression {
+        /* Attention: These methods does not validate the data! */
         size_t qlz_decompressed_size(const void* payload, size_t payload_length);
         bool qlz_decompress_payload(const void* payload, void* buffer, size_t* buffer_size); //Attention: payload & buffer must be differen!
 
diff --git a/test/SQL2Test.cpp b/test/SQL2Test.cpp
index e7285a4..55fdd42 100644
--- a/test/SQL2Test.cpp
+++ b/test/SQL2Test.cpp
@@ -7,6 +7,7 @@
 #include <cassert>
 #include <sql/SqlQuery.h>
 
+#if 0
 template <typename T>
 struct Column {
     constexpr explicit Column(const std::string_view& name) : name{name} { }
@@ -166,4 +167,23 @@ int main() {
     std::string value{};
     insert.add_entry(2, value);
     insert.execute(nullptr);
+}
+#endif
+
+struct A {
+    A() {}
+    ~A() = default;
+};
+
+#include <set>
+int main() {
+    std::set<int> elements{};
+    if(!elements.empty()) {
+        auto it = elements.begin();
+        const int* last_element{&*(it++)}; /* if elements would be empty this would be undefined behaviour */
+        while(it != elements.end()) {
+            const auto now = *it++;
+            const auto diff = last_element - now;
+        }
+    }
 }
\ No newline at end of file