diff --git a/builds/cmake/CMakeLists.txt b/builds/cmake/CMakeLists.txt
index 7fb4654..fdec50c 100644
--- a/builds/cmake/CMakeLists.txt
+++ b/builds/cmake/CMakeLists.txt
@@ -150,7 +150,7 @@ set( boost_LDFLAGS "-L${Boost_LIBRARY_DIR}" )
 
 # Find zmq
 #------------------------------------------------------------------------------
-find_package( Zmq 4.3.4 REQUIRED )
+find_package( Zmq 4.3.5 REQUIRED )
 
 # Find bitcoin-system
 #------------------------------------------------------------------------------
diff --git a/configure.ac b/configure.ac
index 0c46a4a..99f9b0c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -237,13 +237,13 @@ AS_CASE([${with_tests}], [yes],
      AC_MSG_NOTICE([boost_unit_test_framework_LIBS : ${boost_unit_test_framework_LIBS}])],
     [AC_SUBST([boost_unit_test_framework_LIBS], [])])
 
-# Require zmq of at least version 4.3.4 and output ${zmq_CPPFLAGS/LIBS/PKG}.
+# Require zmq of at least version 4.3.5 and output ${zmq_CPPFLAGS/LIBS/PKG}.
 #------------------------------------------------------------------------------
-PKG_CHECK_MODULES([zmq], [libzmq >= 4.3.4],
-    [zmq_INCLUDEDIR="`$PKG_CONFIG --variable=includedir "libzmq >= 4.3.4" 2>/dev/null`"
-     zmq_OTHER_CFLAGS="`$PKG_CONFIG --cflags-only-other "libzmq >= 4.3.4" 2>/dev/null`"],
-    [AC_MSG_ERROR([libzmq >= 4.3.4 is required but was not found.])])
-AC_SUBST([zmq_PKG], ['libzmq >= 4.3.4'])
+PKG_CHECK_MODULES([zmq], [libzmq >= 4.3.5],
+    [zmq_INCLUDEDIR="`$PKG_CONFIG --variable=includedir "libzmq >= 4.3.5" 2>/dev/null`"
+     zmq_OTHER_CFLAGS="`$PKG_CONFIG --cflags-only-other "libzmq >= 4.3.5" 2>/dev/null`"],
+    [AC_MSG_ERROR([libzmq >= 4.3.5 is required but was not found.])])
+AC_SUBST([zmq_PKG], ['libzmq >= 4.3.5'])
 AC_SUBST([zmq_CPPFLAGS], [${zmq_CFLAGS}])
 AS_IF([test x${zmq_INCLUDEDIR} != "x"],
     [AC_SUBST([zmq_ISYS_CPPFLAGS], ["-isystem${zmq_INCLUDEDIR} ${zmq_OTHER_CFLAGS}"])],
diff --git a/install-cmake.sh b/install-cmake.sh
index f295218..ee7a445 100755
--- a/install-cmake.sh
+++ b/install-cmake.sh
@@ -64,8 +64,8 @@ ICU_ARCHIVE="icu4c-55_2-src.tgz"
 
 # ZMQ archive.
 #------------------------------------------------------------------------------
-ZMQ_URL="https://github.com/zeromq/libzmq/releases/download/v4.3.4/zeromq-4.3.4.tar.gz"
-ZMQ_ARCHIVE="zeromq-4.3.4.tar.gz"
+ZMQ_URL="https://github.com/zeromq/libzmq/releases/download/v4.3.5/zeromq-4.3.5.tar.gz"
+ZMQ_ARCHIVE="zeromq-4.3.5.tar.gz"
 
 # Boost archive.
 #------------------------------------------------------------------------------
diff --git a/install-cmakepresets.sh b/install-cmakepresets.sh
index aeb4515..5c2fdb1 100755
--- a/install-cmakepresets.sh
+++ b/install-cmakepresets.sh
@@ -70,8 +70,8 @@ ICU_ARCHIVE="icu4c-55_2-src.tgz"
 
 # ZMQ archive.
 #------------------------------------------------------------------------------
-ZMQ_URL="https://github.com/zeromq/libzmq/releases/download/v4.3.4/zeromq-4.3.4.tar.gz"
-ZMQ_ARCHIVE="zeromq-4.3.4.tar.gz"
+ZMQ_URL="https://github.com/zeromq/libzmq/releases/download/v4.3.5/zeromq-4.3.5.tar.gz"
+ZMQ_ARCHIVE="zeromq-4.3.5.tar.gz"
 
 # Boost archive.
 #------------------------------------------------------------------------------
diff --git a/install.sh b/install.sh
index 0bfb459..743c07d 100755
--- a/install.sh
+++ b/install.sh
@@ -64,8 +64,8 @@ ICU_ARCHIVE="icu4c-55_2-src.tgz"
 
 # ZMQ archive.
 #------------------------------------------------------------------------------
-ZMQ_URL="https://github.com/zeromq/libzmq/releases/download/v4.3.4/zeromq-4.3.4.tar.gz"
-ZMQ_ARCHIVE="zeromq-4.3.4.tar.gz"
+ZMQ_URL="https://github.com/zeromq/libzmq/releases/download/v4.3.5/zeromq-4.3.5.tar.gz"
+ZMQ_ARCHIVE="zeromq-4.3.5.tar.gz"
 
 # Boost archive.
 #------------------------------------------------------------------------------
diff --git a/libbitcoin-protocol.pc.in b/libbitcoin-protocol.pc.in
index a205dac..652a8e2 100644
--- a/libbitcoin-protocol.pc.in
+++ b/libbitcoin-protocol.pc.in
@@ -25,7 +25,7 @@ Version: @PACKAGE_VERSION@
 #==============================================================================
 # Dependencies that publish package configuration.
 #------------------------------------------------------------------------------
-Requires: libzmq >= 4.3.4 libbitcoin-system >= 4.0.0
+Requires: libzmq >= 4.3.5 libbitcoin-system >= 4.0.0
 
 # Include directory and any other required compiler flags.
 #------------------------------------------------------------------------------