diff --git a/CMakeLists.txt b/CMakeLists.txt
index d27a4b24..dc775c46 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -701,9 +701,7 @@ target_include_directories(${MINIZIP_TARGET} PUBLIC
 if(MZ_COMPAT)
     target_include_directories(${MINIZIP_TARGET} PUBLIC
         $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/compat/>
-        $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>
-        ${ZLIB_SOURCE_DIR}
-        ${ZLIB_BINARY_DIR})
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>)
 endif()
 
 # Install files
diff --git a/compat/crypt.h b/compat/crypt.h
index 6e9b51ff..516013dd 100644
--- a/compat/crypt.h
+++ b/compat/crypt.h
@@ -26,7 +26,10 @@
 */
 
 #ifndef _ZLIB_H
-#  if (ZLIB_VERNUM & 0xf != 0xf) && (ZLIB_VERNUM < 0x1270)
+#  ifndef ZLIB_VERNUM
+    /* HAVE_ZLIB but no ZLIB_VERNUM? */
+    typedef uint32_t z_crc_t;
+#  elif (ZLIB_VERNUM & 0xf != 0xf) && (ZLIB_VERNUM < 0x1270)
     /* Define z_crc_t in zlib 1.2.6 and less */
     typedef unsigned long z_crc_t;
 #  elif (ZLIB_VERNUM & 0xf == 0xf) && (ZLIB_VERNUM < 0x12df)
diff --git a/compat/ioapi.h b/compat/ioapi.h
index d1d5b094..88bf2c4b 100644
--- a/compat/ioapi.h
+++ b/compat/ioapi.h
@@ -5,7 +5,11 @@
 #include <stdint.h>
 
 #ifndef _ZLIB_H
-#include "zlib.h"
+#  if __has_include(<zlib.h>)
+#    include <zlib.h>
+#  elif __has_include(<zlib-ng.h>)
+#    include <zlib-ng.h>
+#  endif
 #endif
 
 typedef uint64_t ZPOS64_T;
diff --git a/mz_crypt.c b/mz_crypt.c
index 2971f84c..f4a6c3ee 100644
--- a/mz_crypt.c
+++ b/mz_crypt.c
@@ -34,7 +34,10 @@ int32_t mz_crypt_rand(uint8_t *buf, int32_t size) {
 
 uint32_t mz_crypt_crc32_update(uint32_t value, const uint8_t *buf, int32_t size) {
 #if defined(HAVE_ZLIB)
-#  if (ZLIB_VERNUM & 0xf != 0xf) && (ZLIB_VERNUM < 0x1270)
+#  ifndef ZLIB_VERNUM
+    /* HAVE_ZLIB but no ZLIB_VERNUM? */
+    typedef uint32_t z_crc_t;
+#  elif (ZLIB_VERNUM & 0xf != 0xf) && (ZLIB_VERNUM < 0x1270)
     /* Define z_crc_t in zlib 1.2.6 and less */
     typedef unsigned long z_crc_t;
 #  elif (ZLIB_VERNUM & 0xf == 0xf) && (ZLIB_VERNUM < 0x12df)