diff --git a/js/src/jsutil.h b/js/src/jsutil.h
index 7472ac0e4b9..edbc6e877de 100644
--- a/js/src/jsutil.h
+++ b/js/src/jsutil.h
@@ -14,12 +14,10 @@
 #include "mozilla/Assertions.h"
 #include "mozilla/Compiler.h"
 #include "mozilla/GuardObjects.h"
-#include "mozilla/PodOperations.h"
 
 #include <limits.h>
 
 #include "js/Utility.h"
-#include "js/Value.h"
 
 #define JS_ALWAYS_TRUE(expr)      MOZ_ALWAYS_TRUE(expr)
 #define JS_ALWAYS_FALSE(expr)     MOZ_ALWAYS_FALSE(expr)
@@ -280,31 +278,20 @@ ClearAllBitArrayElements(size_t* array, size_t length)
 }  /* namespace js */
 
 static inline void*
-Poison(void* ptr, uint8_t value, size_t num)
+Poison(void* ptr, int value, size_t num)
 {
-    static bool poison = getenv("JSGC_DISABLE_POISONING");
-    if (poison) {
-        // Without a valid Value tag, a poisoned Value may look like a valid
-        // floating point number. To ensure that we crash more readily when
-        // observing a poisoned Value, we make the poison an invalid ObjectValue.
-        uintptr_t obj;
-        memset(&obj, value, sizeof(obj));
-#if defined(JS_PUNBOX64)
-        obj >>= JSVAL_TAG_SHIFT;
-#endif
-        jsval_layout layout = OBJECT_TO_JSVAL_IMPL((JSObject*)obj);
-
-        size_t value_count = num / sizeof(jsval_layout);
-        size_t byte_count = num % sizeof(jsval_layout);
-        mozilla::PodSet((jsval_layout*)ptr, layout, value_count);
-        if (byte_count) {
-            uint8_t* bytes = static_cast<uint8_t*>(ptr);
-            uint8_t* end = bytes + num;
-            mozilla::PodSet(end - byte_count, value, byte_count);
-        }
-        return ptr;
+    static bool inited = false;
+    static bool poison = true;
+    if (!inited) {
+        char* env = getenv("JSGC_DISABLE_POISONING");
+        if (env)
+            poison = false;
+        inited = true;
     }
 
+    if (poison)
+        return memset(ptr, value, num);
+
     return nullptr;
 }
 
diff --git a/mfbt/PodOperations.h b/mfbt/PodOperations.h
index dd4e2143097..9d7b5850ab7 100644
--- a/mfbt/PodOperations.h
+++ b/mfbt/PodOperations.h
@@ -88,18 +88,6 @@ PodAssign(T* aDst, const T* aSrc)
          sizeof(T));
 }
 
-/**
- * Set the first |aNElem| T elements in |aDst| to |aSrc|.
- */
-template<typename T>
-static MOZ_ALWAYS_INLINE void
-PodSet(T* aDst, T aSrc, size_t aNElem)
-{
-  for (const T* dstend = aDst + aNElem; aDst < dstend; aDst++) {
-    *aDst = aSrc;
-  }
-}
-
 /**
  * Copy |aNElem| T elements from |aSrc| to |aDst|.  The two memory ranges must
  * not overlap!