diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 9bb3097..d69c665 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -36,6 +36,7 @@ else()
     endif()
     find_package(WolfSSL)
     find_package(MbedTLS)
+    find_package(ZLIB)
 
     if(RTTY_USE_OPENSSL)
         if (NOT OPENSSL_FOUND)
@@ -76,7 +77,7 @@ else()
     elseif(RTTY_USE_MBEDTLS)
         set(SSL_NAME "MbedTLS(PolarSSL)")
         set(SSL_INC ${MBEDTLS_INCLUDE_DIR})
-        set(SSL_LIB ${MBEDTLS_LIBRARIES})
+        set(SSL_LIB ${MBEDTLS_LIBRARIES} ${ZLIB_LIBRARIES})
         set(RTTY_HAVE_MBEDTLS_CONFIG 1)
     endif()