diff --git a/zconf.h b/zconf.h
index fbe7a79..ea3b6d6 100644
--- a/zconf.h
+++ b/zconf.h
@@ -511,6 +511,8 @@ typedef uLong FAR uLongf;
 
 #if !defined(_WIN32) && defined(Z_LARGE64)
 #  define z_off64_t off64_t
+#elif defined(__MINGW32__)
+#  define z_off64_t long long
 #elif defined(_WIN32) && !defined(__GNUC__)
 #  define z_off64_t __int64
 #elif defined(__GO32__)
diff --git a/zconf.h.cmakein b/zconf.h.cmakein
index 96e9296..0eced14 100644
--- a/zconf.h.cmakein
+++ b/zconf.h.cmakein
@@ -513,6 +513,8 @@ typedef uLong FAR uLongf;
 
 #if !defined(_WIN32) && defined(Z_LARGE64)
 #  define z_off64_t off64_t
+#elif defined(__MINGW32__)
+#  define z_off64_t long long
 #elif defined(_WIN32) && !defined(__GNUC__)
 #  define z_off64_t __int64
 #elif defined(__GO32__)
diff --git a/zconf.h.in b/zconf.h.in
index fbe7a79..ea3b6d6 100644
--- a/zconf.h.in
+++ b/zconf.h.in
@@ -511,6 +511,8 @@ typedef uLong FAR uLongf;
 
 #if !defined(_WIN32) && defined(Z_LARGE64)
 #  define z_off64_t off64_t
+#elif defined(__MINGW32__)
+#  define z_off64_t long long
 #elif defined(_WIN32) && !defined(__GNUC__)
 #  define z_off64_t __int64
 #elif defined(__GO32__)