--- a/memory/jemalloc/jemalloc.c
+++ b/memory/jemalloc/jemalloc.c
@@ -77,16 +77,20 @@
  *   |                           | 1020 kB |
  *   |=====================================|
  *   | Huge                      |    1 MB |
  *   |                           |    2 MB |
  *   |                           |    3 MB |
  *   |                           |     ... |
  *   |=====================================|
  *
+ * NOTE: Due to Mozilla bug 691003, we cannot reserve less than one word for an
+ * allocation on Linux or Mac.  So on 32-bit *nix, the smallest bucket size is
+ * 4 bytes, and on 64-bit, the smallest bucket size is 8 bytes.
+ *
  * A different mechanism is used for each category:
  *
  *   Small : Each size class is segregated into its own set of runs.  Each run
  *           maintains a bitmap of which regions are free/allocated.
  *
  *   Large : Each allocation is backed by a dedicated run.  Metadata are stored
  *           in the associated arena chunk header maps.
  *
@@ -421,17 +425,17 @@ static const bool __isthreaded = true;
 #endif
 
 #  define inline
 #endif
 
 /* Size of stack-allocated buffer passed to strerror_r(). */
 #define	STRERROR_BUF		64
 
-/* Minimum alignment of allocations is 2^QUANTUM_2POW_MIN bytes. */
+/* Minimum alignment of non-tiny allocations is 2^QUANTUM_2POW_MIN bytes. */
 #  define QUANTUM_2POW_MIN      4
 #ifdef MOZ_MEMORY_SIZEOF_PTR_2POW
 #  define SIZEOF_PTR_2POW		MOZ_MEMORY_SIZEOF_PTR_2POW
 #else
 #  define SIZEOF_PTR_2POW       2
 #endif
 #define PIC
 #ifndef MOZ_MEMORY_DARWIN
@@ -510,18 +514,25 @@ static const bool __isthreaded = true;
 /*
  * Maximum size of L1 cache line.  This is used to avoid cache line aliasing,
  * so over-estimates are okay (up to a point), but under-estimates will
  * negatively affect performance.
  */
 #define	CACHELINE_2POW		6
 #define	CACHELINE		((size_t)(1U << CACHELINE_2POW))
 
-/* Smallest size class to support. */
+/*
+ * Smallest size class to support.  On Linux and Mac, even malloc(1) must
+ * reserve a word's worth of memory (see Mozilla bug 691003).
+ */
+#ifdef MOZ_MEMORY_WINDOWS
 #define	TINY_MIN_2POW		1
+#else
+#define TINY_MIN_2POW           (sizeof(void*) == 8 ? 3 : 2)
+#endif
 
 /*
  * Maximum size class that is a multiple of the quantum, but not (necessarily)
  * a power of 2.  Above this size, allocations are rounded up to the nearest
  * power of 2.
  */
 #define	SMALL_MAX_2POW_DEFAULT	9
 #define	SMALL_MAX_DEFAULT	(1U << SMALL_MAX_2POW_DEFAULT)