diff --git a/travis/dockerfiles/Dockerfile.debian-9 b/travis/dockerfiles/Dockerfile.debian-9
index 2a2c7989c..edf0100b1 100644
--- a/travis/dockerfiles/Dockerfile.debian-9
+++ b/travis/dockerfiles/Dockerfile.debian-9
@@ -11,4 +11,5 @@ RUN apt-get update -qq && apt-get install -y --no-install-recommends \
     libgmp-dev \
     libginac-dev \
     automake \
-    libglpk-dev
+    libglpk-dev \
+    libz3-dev
diff --git a/travis/dockerfiles/Dockerfile.ubuntu-16.10 b/travis/dockerfiles/Dockerfile.ubuntu-16.10
index 541f8b64c..966857553 100644
--- a/travis/dockerfiles/Dockerfile.ubuntu-16.10
+++ b/travis/dockerfiles/Dockerfile.ubuntu-16.10
@@ -12,4 +12,5 @@ RUN apt-get update -qq && apt-get install -y --no-install-recommends \
     libginac-dev \
     automake \
     libglpk-dev \
-    libhwloc-dev
+    libhwloc-dev \
+    libz3-dev
diff --git a/travis/install_osx.sh b/travis/install_osx.sh
index 1a581f8b6..4ebee5484 100755
--- a/travis/install_osx.sh
+++ b/travis/install_osx.sh
@@ -59,6 +59,7 @@ install_brew_package cln
 install_brew_package ginac
 install_brew_package doxygen
 install_brew_package boost --c++11
+install_brew_package z3 # optional
 brew tap homebrew/science
 install_brew_package homebrew/science/glpk
 install_brew_package homebrew/science/hwloc