diff --git a/ghdl-formal.Dockerfile b/ghdl-formal.Dockerfile
index ba6a1b0..512da0a 100644
--- a/ghdl-formal.Dockerfile
+++ b/ghdl-formal.Dockerfile
@@ -2,7 +2,7 @@
 
 FROM symbiyosys as symbiyosys-ghdl
 
-ARG LLVM_VER="7"
+ARG LLVM_VER="11"
 
 RUN apt-get update -qq && \
     DEBIAN_FRONTEND=noninteractive apt-get -y install --no-install-recommends \
@@ -36,16 +36,18 @@ RUN cd /root && \
 
 # GHDL-formal
 
-FROM debian:buster-slim AS ghdl-formal
+FROM debian:bullseye-slim AS ghdl-formal
+
+ARG LLVM_VER="11"
 
 # Get runtime dependencies
 RUN apt-get update -qq && \
     DEBIAN_FRONTEND=noninteractive apt-get -y install --no-install-recommends \
     ca-certificates \
-    libreadline7 \
+    libreadline8 \
     libtcl8.6 \
-    libgnat-8 \
-    libllvm7 \
+    libgnat-10 \
+    libllvm$LLVM_VER \
     gcc \
     libc6-dev \
     zlib1g-dev \
diff --git a/symbiyosys.Dockerfile b/symbiyosys.Dockerfile
index f3c66b8..a11262e 100644
--- a/symbiyosys.Dockerfile
+++ b/symbiyosys.Dockerfile
@@ -1,4 +1,4 @@
-FROM debian:buster-slim as yosys
+FROM debian:bullseye-slim as yosys
 
 ## YOSYS ##
 
@@ -17,7 +17,6 @@ RUN apt-get update -qq && \
     graphviz \
     xdot \
     pkg-config \
-    python3 \
     libboost-system-dev \
     libboost-python-dev \
     libboost-filesystem-dev \
@@ -51,8 +50,9 @@ RUN apt-get update -qq && \
     ninja-build \
     g++ \
     python-setuptools \
-    python-pip \
-    python-wheel \
+    python3-pip \
+    python-wheel-common \
+    python-dev-is-python2 \
     mercurial && \
     apt-get autoclean && apt-get clean && apt-get -y autoremove && \
     rm -rf /var/lib/apt/lists/* && \
@@ -65,7 +65,7 @@ RUN apt-get update -qq && \
     cd .. && \
     git clone https://github.com/Z3Prover/z3.git z3 && \
     cd z3 && \
-    python scripts/mk_make.py && \
+    python3 scripts/mk_make.py && \
     cd build && \
     make -j$(nproc) PREFIX=/opt/z3 && \
     make install PREFIX=/opt/z3 && \