diff --git a/Dockerfile b/Dockerfile
index dec952af41..8779fee570 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -14,6 +14,7 @@ ARG DEBIAN_FRONTEND=noninteractive
 RUN apt-get update && \
     apt-get -y install --no-install-suggests --no-install-recommends \
     automake \
+    ninja-build \
     bison flex \
     build-essential \
     git \
@@ -26,7 +27,7 @@ RUN apt-get update && \
     gnuplot-nox \
     && rm -rf /var/lib/apt/lists/*
 
-RUN echo "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-11 main" >> /etc/apt/sources.list && \
+RUN echo "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-12 main" >> /etc/apt/sources.list && \
     wget -qO - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -
 
 RUN echo "deb http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu focal main" >> /etc/apt/sources.list && \
@@ -35,17 +36,17 @@ RUN echo "deb http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu focal main
 RUN apt-get update && apt-get full-upgrade -y && \
     apt-get -y install --no-install-suggests --no-install-recommends \
     gcc-10 g++-10 gcc-10-plugin-dev gcc-10-multilib gdb lcov \
-    clang-11 clang-tools-11 libc++1-11 libc++-11-dev \
-    libc++abi1-11 libc++abi-11-dev libclang1-11 libclang-11-dev \
-    libclang-common-11-dev libclang-cpp11 libclang-cpp11-dev liblld-11 \
-    liblld-11-dev liblldb-11 liblldb-11-dev libllvm11 libomp-11-dev \
-    libomp5-11 lld-11 lldb-11 llvm-11 llvm-11-dev llvm-11-runtime llvm-11-tools \
+    clang-12 clang-tools-12 libc++1-12 libc++-12-dev \
+    libc++abi1-12 libc++abi-12-dev libclang1-12 libclang-12-dev \
+    libclang-common-12-dev libclang-cpp12 libclang-cpp12-dev liblld-12 \
+    liblld-12-dev liblldb-12 liblldb-12-dev libllvm12 libomp-12-dev \
+    libomp5-12 lld-12 lldb-12 llvm-12 llvm-12-dev llvm-12-runtime llvm-12-tools \
     && rm -rf /var/lib/apt/lists/*
 
 RUN update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-10 0
 RUN update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-10 0
 
-ENV LLVM_CONFIG=llvm-config-11
+ENV LLVM_CONFIG=llvm-config-12
 ENV AFL_SKIP_CPUFREQ=1
 
 RUN git clone https://github.com/vanhauser-thc/afl-cov /afl-cov
diff --git a/instrumentation/afl-llvm-lto-instrumentation.so.cc b/instrumentation/afl-llvm-lto-instrumentation.so.cc
index 13dca8c42c..fa494f4465 100644
--- a/instrumentation/afl-llvm-lto-instrumentation.so.cc
+++ b/instrumentation/afl-llvm-lto-instrumentation.so.cc
@@ -69,7 +69,7 @@ class AFLLTOPass : public ModulePass {
 
     if (getenv("AFL_DEBUG")) debug = 1;
     if ((ptr = getenv("AFL_LLVM_LTO_STARTID")) != NULL)
-      if ((afl_global_id = atoi(ptr)) < 0 || afl_global_id >= MAP_SIZE)
+      if ((afl_global_id = (uint32_t)atoi(ptr)) < 0 || afl_global_id >= MAP_SIZE)
         FATAL("AFL_LLVM_LTO_STARTID value of \"%s\" is not between 0 and %u\n",
               ptr, MAP_SIZE - 1);
 
@@ -88,7 +88,7 @@ class AFLLTOPass : public ModulePass {
   bool runOnModule(Module &M) override;
 
  protected:
-  int      afl_global_id = 1, autodictionary = 1;
+  uint32_t afl_global_id = 1, autodictionary = 1;
   uint32_t function_minimum_size = 1;
   uint32_t inst_blocks = 0, inst_funcs = 0, total_instr = 0;
   uint64_t map_addr = 0x10000;
@@ -800,7 +800,7 @@ bool AFLLTOPass::runOnModule(Module &M) {
 
           if (documentFile) {
 
-            fprintf(documentFile, "ModuleID=%llu Function=%s edgeID=%d\n",
+            fprintf(documentFile, "ModuleID=%llu Function=%s edgeID=%u\n",
                     moduleID, F.getName().str().c_str(), afl_global_id);
 
           }
@@ -872,10 +872,10 @@ bool AFLLTOPass::runOnModule(Module &M) {
     while ((map = map >> 1))
       pow2map++;
     WARNF(
-        "We have %d blocks to instrument but the map size is only %u. Either "
+        "We have %u blocks to instrument but the map size is only %u. Either "
         "edit config.h and set MAP_SIZE_POW2 from %d to %u, then recompile "
         "afl-fuzz and llvm_mode and then make this target - or set "
-        "AFL_MAP_SIZE with at least size %d when running afl-fuzz with this "
+        "AFL_MAP_SIZE with at least size %u when running afl-fuzz with this "
         "target.",
         afl_global_id, MAP_SIZE, MAP_SIZE_POW2, pow2map, afl_global_id);
 
@@ -925,7 +925,7 @@ bool AFLLTOPass::runOnModule(Module &M) {
 
       uint32_t write_loc = afl_global_id;
 
-      if (afl_global_id % 8) write_loc = (((afl_global_id + 8) >> 3) << 3);
+      if (afl_global_id % 32) write_loc = (((afl_global_id + 32) >> 4) << 4);
 
       GlobalVariable *AFLFinalLoc = new GlobalVariable(
           M, Int32Ty, true, GlobalValue::ExternalLinkage, 0, "__afl_final_loc");
diff --git a/unicorn_mode/build_unicorn_support.sh b/unicorn_mode/build_unicorn_support.sh
index c32eb3e1f8..f1d028f85a 100755
--- a/unicorn_mode/build_unicorn_support.sh
+++ b/unicorn_mode/build_unicorn_support.sh
@@ -147,6 +147,8 @@ if [ "$PREREQ_NOTFOUND" = "1" ]; then
   exit 1
 fi
 
+unset CFLAGS
+
 echo "[+] All checks passed!"
 
 echo "[*] Making sure unicornafl is checked out"