diff --git a/CMakeLists.txt b/CMakeLists.txt
index 83f0ffd61..aa7359121 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -119,7 +119,6 @@ unset(CMAKE_COMPILE_FLAGS)
 set(ZLIB_PC ${zlib_BINARY_DIR}/zlib.pc)
 configure_file(${zlib_SOURCE_DIR}/zlib.pc.cmakein ${ZLIB_PC} @ONLY)
 configure_file(${zlib_BINARY_DIR}/zconf.h.cmakein ${zlib_BINARY_DIR}/zconf.h)
-include_directories(${zlib_BINARY_DIR} ${zlib_SOURCE_DIR})
 
 # ============================================================================
 # zlib
@@ -172,7 +171,8 @@ if(ZLIB_BUILD_SHARED)
                $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
     target_compile_definitions(
         zlib
-        PRIVATE $<$<BOOL:NOT:${HAVE_FSEEKO}>:NO_FSEEKO>
+        PRIVATE ZLIB_BUILD
+                $<$<BOOL:NOT:${HAVE_FSEEKO}>:NO_FSEEKO>
                 $<$<BOOL:${HAVE___ATTR__VIS_HIDDEN}>:HAVE_HIDDEN>
                 $<$<BOOL:${MSVC}>:_CRT_SECURE_NO_DEPRECATE>
                 $<$<BOOL:${MSVC}>:_CRT_NONSTDC_NO_DEPRECATE>
@@ -214,7 +214,8 @@ if(ZLIB_BUILD_STATIC)
                $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
     target_compile_definitions(
         zlibstatic
-        PRIVATE $<$<BOOL:NOT:${HAVE_FSEEKO}>:NO_FSEEKO>
+        PRIVATE ZLIB_BUILD
+                $<$<BOOL:NOT:${HAVE_FSEEKO}>:NO_FSEEKO>
                 $<$<BOOL:${HAVE___ATTR__VIS_HIDDEN}>:HAVE_HIDDEN>
                 $<$<BOOL:${MSVC}>:_CRT_SECURE_NO_DEPRECATE>
                 $<$<BOOL:${MSVC}>:_CRT_NONSTDC_NO_DEPRECATE>
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 46c07ebf6..0d2844d8c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -16,6 +16,7 @@ endfunction()
 if(ZLIB_BUILD_SHARED)
     add_executable(zlib_example example.c)
     target_link_libraries(zlib_example ZLIB::ZLIB)
+    target_compile_definitions(zlib_example PRIVATE ZLIB_BUILD)
     add_test(NAME zlib_example COMMAND zlib_example)
 
     add_executable(minigzip minigzip.c)
@@ -38,7 +39,7 @@ if(ZLIB_BUILD_SHARED)
         add_executable(zlib_example64 example.c)
         target_compile_definitions(
             zlib_example64
-            PRIVATE LARGEFILE64_SOURCE=1
+            PRIVATE ZLIB_BUILD
                     $<$<BOOL:${HAVE___ATTR__VIS_HIDDEN}>:HAVE_HIDDEN>)
         target_link_libraries(zlib_example64 ZLIB::ZLIB)
         add_test(NAME zlib_example64 COMMAND zlib_example64)
@@ -61,7 +62,8 @@ if(ZLIB_BUILD_STATIC)
     target_link_libraries(zlib_static_example ZLIB::ZLIBSTATIC)
     target_compile_definitions(
         zlib_static_example
-        PRIVATE $<$<BOOL:${HAVE___ATTR__VIS_HIDDEN}>:HAVE_HIDDEN>)
+        PRIVATE ZLIB_BUILD
+                $<$<BOOL:${HAVE___ATTR__VIS_HIDDEN}>:HAVE_HIDDEN>)
     add_test(NAME zlib_static_example COMMAND zlib_static_example)
 
     add_executable(static_minigzip minigzip.c)
@@ -116,7 +118,7 @@ if(ZLIB_BUILD_STATIC)
         add_executable(zlib_static_example64 example.c)
         target_compile_definitions(
             zlib_static_example64
-            PRIVATE LARGEFILE64_SOURCE=1
+            PRIVATE ZLIB_BUILD
                     $<$<BOOL:${HAVE___ATTR__VIS_HIDDEN}>:HAVE_HIDDEN>)
         target_link_libraries(zlib_static_example64 ZLIB::ZLIBSTATIC)
         add_test(NAME zlib_static_example64 COMMAND zlib_static_example64)
diff --git a/zlib.h b/zlib.h
index 8cafa325a..c75090b0f 100644
--- a/zlib.h
+++ b/zlib.h
@@ -31,7 +31,11 @@
 #ifndef ZLIB_H
 #define ZLIB_H
 
-#include <zconf.h>
+#ifdef ZLIB_BUILD
+#  include <zconf.h>
+#else
+# include "zconf.h"
+#endif
 
 #ifdef __cplusplus
 extern "C" {