diff --git a/zconf.h b/zconf.h
index 0a9f22c..fbe7a79 100644
--- a/zconf.h
+++ b/zconf.h
@@ -511,12 +511,12 @@ typedef uLong FAR uLongf;
 
 #if !defined(_WIN32) && defined(Z_LARGE64)
 #  define z_off64_t off64_t
+#elif defined(_WIN32) && !defined(__GNUC__)
+#  define z_off64_t __int64
+#elif defined(__GO32__)
+#  define z_off64_t offset_t
 #else
-#  if defined(_WIN32) && !defined(__GNUC__)
-#    define z_off64_t __int64
-#  else
-#    define z_off64_t z_off_t
-#  endif
+#  define z_off64_t z_off_t
 #endif
 
 /* MVS linker does not support external names larger than 8 bytes */
diff --git a/zconf.h.cmakein b/zconf.h.cmakein
index a5cb288..96e9296 100644
--- a/zconf.h.cmakein
+++ b/zconf.h.cmakein
@@ -513,12 +513,12 @@ typedef uLong FAR uLongf;
 
 #if !defined(_WIN32) && defined(Z_LARGE64)
 #  define z_off64_t off64_t
+#elif defined(_WIN32) && !defined(__GNUC__)
+#  define z_off64_t __int64
+#elif defined(__GO32__)
+#  define z_off64_t offset_t
 #else
-#  if defined(_WIN32) && !defined(__GNUC__)
-#    define z_off64_t __int64
-#  else
-#    define z_off64_t z_off_t
-#  endif
+#  define z_off64_t z_off_t
 #endif
 
 /* MVS linker does not support external names larger than 8 bytes */
diff --git a/zconf.h.in b/zconf.h.in
index 0a9f22c..fbe7a79 100644
--- a/zconf.h.in
+++ b/zconf.h.in
@@ -511,12 +511,12 @@ typedef uLong FAR uLongf;
 
 #if !defined(_WIN32) && defined(Z_LARGE64)
 #  define z_off64_t off64_t
+#elif defined(_WIN32) && !defined(__GNUC__)
+#  define z_off64_t __int64
+#elif defined(__GO32__)
+#  define z_off64_t offset_t
 #else
-#  if defined(_WIN32) && !defined(__GNUC__)
-#    define z_off64_t __int64
-#  else
-#    define z_off64_t z_off_t
-#  endif
+#  define z_off64_t z_off_t
 #endif
 
 /* MVS linker does not support external names larger than 8 bytes */