diff --git a/malloc/malloc.c b/malloc/malloc.c
index f8e7250..de6d7fa 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -4146,6 +4146,7 @@ _int_free (mstate av, mchunkptr p, int have_lock)
   mchunkptr bck;               /* misc temp for linking */
   mchunkptr fwd;               /* misc temp for linking */
 
+  static int alternate;
   size = chunksize (p);
 
   /* Little security check which won't hurt performance: the
@@ -4364,8 +4365,14 @@ _int_free (mstate av, mchunkptr p, int have_lock)
       if (av == &main_arena) {
 #ifndef MORECORE_CANNOT_TRIM
 	if ((unsigned long)(chunksize(av->top)) >=
-	    (unsigned long)(mp_.trim_threshold))
-	  systrim(mp_.top_pad, av);
+            (unsigned long)(mp_.trim_threshold)) {
+        if (alternate) {
+            systrim(mp_.top_pad, av);
+            alternate = 0;
+        } else {
+            alternate = 1;
+        }
+    }
 #endif
       } else {
 	/* Always try heap_trim(), even if the top chunk is not