diff --git a/tools/trace-malloc/lib/nsTraceMalloc.c b/tools/trace-malloc/lib/nsTraceMalloc.c
index e3d9bf6ff84..c51faeba1fc 100644
--- a/tools/trace-malloc/lib/nsTraceMalloc.c
+++ b/tools/trace-malloc/lib/nsTraceMalloc.c
@@ -1712,7 +1712,8 @@ PR_IMPLEMENT(int) NS_TraceMallocStartupArgs(int argc, char* argv[])
         }
     }
 
-    NS_TraceMallocStartup(logfd);
+    if (logfd >= 0)
+        NS_TraceMallocStartup(logfd);
     return argc;
 }
 
diff --git a/xpcom/base/nsTraceMalloc.c b/xpcom/base/nsTraceMalloc.c
index e3d9bf6ff84..c51faeba1fc 100644
--- a/xpcom/base/nsTraceMalloc.c
+++ b/xpcom/base/nsTraceMalloc.c
@@ -1712,7 +1712,8 @@ PR_IMPLEMENT(int) NS_TraceMallocStartupArgs(int argc, char* argv[])
         }
     }
 
-    NS_TraceMallocStartup(logfd);
+    if (logfd >= 0)
+        NS_TraceMallocStartup(logfd);
     return argc;
 }