diff --git a/util/zlib-extra.c b/util/zlib-extra.c
index 2d2d2414..3a75e504 100644
--- a/util/zlib-extra.c
+++ b/util/zlib-extra.c
@@ -85,3 +85,10 @@ gz_error_string (util_status_t status, gzFile file)
     else
 	return util_error_string (status);
 }
+
+const char *
+gzerror_str(gzFile file)
+{
+    int dummy;
+    return gzerror (file, &dummy);
+}
diff --git a/util/zlib-extra.h b/util/zlib-extra.h
index 296dc914..e9925c98 100644
--- a/util/zlib-extra.h
+++ b/util/zlib-extra.h
@@ -29,8 +29,8 @@ gz_error_string (util_status_t status, gzFile stream);
 
 /* Call gzerror with a dummy errno argument, the docs don't promise to
  * support the NULL case */
-inline const char *
-gzerror_str(gzFile file) { int dummy; return gzerror (file, &dummy); }
+const char *
+gzerror_str(gzFile file);
 
 #ifdef __cplusplus
 }