diff --git a/include/haproxy/compat.h b/include/haproxy/compat.h
index 97cde46c3..581141c1f 100644
--- a/include/haproxy/compat.h
+++ b/include/haproxy/compat.h
@@ -240,6 +240,15 @@ typedef struct { } empty_t;
 #endif
 #endif
 
+/* malloc_trim() can be very convenient to reclaim unused memory especially
+ * from huge pattern files. It's available (and really usable) in glibc 2.8 and
+ * above.
+ */
+#if (defined(__GNU_LIBRARY__) && (__GLIBC__ > 2 || __GLIBC__ == 2 && __GLIBC_MINOR__ >= 8))
+#include <malloc.h>
+#define HA_HAVE_MALLOC_TRIM
+#endif
+
 /* Max number of file descriptors we send in one sendmsg(). Linux seems to be
  * able to send 253 fds per sendmsg(), not sure about the other OSes.
  */