diff --git a/lib/decompress/huf_decompress.c b/lib/decompress/huf_decompress.c
index 5bbdef49a..b8795efb5 100644
--- a/lib/decompress/huf_decompress.c
+++ b/lib/decompress/huf_decompress.c
@@ -164,17 +164,18 @@ static size_t HUF_initFastDStream(BYTE const* ip) {
  * op [in/out] - The output pointers, must be updated to reflect what is written.
  * bits [in/out] - The bitstream containers, must be updated to reflect the current state.
  * dt [in] - The decoding table.
- * ilimit [in] - The input limit, stop when any input pointer is below ilimit.
+ * ilowest [in] - The beginning of the valid range of the input. Decoders may read
+ *                down to this pointer. It may be below iend[0].
  * oend [in] - The end of the output stream. op[3] must not cross oend.
  * iend [in] - The end of each input stream. ip[i] may cross iend[i],
- *             as long as it is above ilimit, but that indicates corruption.
+ *             as long as it is above ilowest, but that indicates corruption.
  */
 typedef struct {
     BYTE const* ip[4];
     BYTE* op[4];
     U64 bits[4];
     void const* dt;
-    BYTE const* ilimit;
+    BYTE const* ilowest;
     BYTE* oend;
     BYTE const* iend[4];
 } HUF_DecompressFastArgs;
@@ -192,7 +193,7 @@ static size_t HUF_DecompressFastArgs_init(HUF_DecompressFastArgs* args, void* ds
     void const* dt = DTable + 1;
     U32 const dtLog = HUF_getDTableDesc(DTable).tableLog;
 
-    const BYTE* const ilimit = (const BYTE*)src + 6 + 8;
+    const BYTE* const istart = (const BYTE*)src;
 
     BYTE* const oend = ZSTD_maybeNullPtrAdd((BYTE*)dst, dstSize);
 
@@ -215,7 +216,6 @@ static size_t HUF_DecompressFastArgs_init(HUF_DecompressFastArgs* args, void* ds
 
     /* Read the jump table. */
     {
-        const BYTE* const istart = (const BYTE*)src;
         size_t const length1 = MEM_readLE16(istart);
         size_t const length2 = MEM_readLE16(istart+2);
         size_t const length3 = MEM_readLE16(istart+4);
@@ -227,10 +227,8 @@ static size_t HUF_DecompressFastArgs_init(HUF_DecompressFastArgs* args, void* ds
 
         /* HUF_initFastDStream() requires this, and this small of an input
          * won't benefit from the ASM loop anyways.
-         * length1 must be >= 16 so that ip[0] >= ilimit before the loop
-         * starts.
          */
-        if (length1 < 16 || length2 < 8 || length3 < 8 || length4 < 8)
+        if (length1 < 8 || length2 < 8 || length3 < 8 || length4 < 8)
             return 0;
         if (length4 > srcSize) return ERROR(corruption_detected);   /* overflow */
     }
@@ -262,11 +260,12 @@ static size_t HUF_DecompressFastArgs_init(HUF_DecompressFastArgs* args, void* ds
     args->bits[2] = HUF_initFastDStream(args->ip[2]);
     args->bits[3] = HUF_initFastDStream(args->ip[3]);
 
-    /* If ip[] >= ilimit, it is guaranteed to be safe to
-        * reload bits[]. It may be beyond its section, but is
-        * guaranteed to be valid (>= istart).
-        */
-    args->ilimit = ilimit;
+    /* The decoders must be sure to never read beyond ilowest.
+     * This is lower than iend[0], but allowing decoders to read
+     * down to ilowest can allow an extra iteration or two in the
+     * fast loop.
+     */
+    args->ilowest = istart;
 
     args->oend = oend;
     args->dt = dt;
@@ -291,7 +290,7 @@ static size_t HUF_initRemainingDStream(BIT_DStream_t* bit, HUF_DecompressFastArg
     assert(sizeof(size_t) == 8);
     bit->bitContainer = MEM_readLEST(args->ip[stream]);
     bit->bitsConsumed = ZSTD_countTrailingZeros64(args->bits[stream]);
-    bit->start = (const char*)args->iend[0];
+    bit->start = (const char*)args->ilowest;
     bit->limitPtr = bit->start + sizeof(size_t);
     bit->ptr = (const char*)args->ip[stream];
 
@@ -717,7 +716,7 @@ void HUF_decompress4X1_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs*
     BYTE* op[4];
     U16 const* const dtable = (U16 const*)args->dt;
     BYTE* const oend = args->oend;
-    BYTE const* const ilimit = args->ilimit;
+    BYTE const* const ilowest = args->ilowest;
 
     /* Copy the arguments to local variables */
     ZSTD_memcpy(&bits, &args->bits, sizeof(bits));
@@ -735,7 +734,7 @@ void HUF_decompress4X1_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs*
 #ifndef NDEBUG
         for (stream = 0; stream < 4; ++stream) {
             assert(op[stream] <= (stream == 3 ? oend : op[stream + 1]));
-            assert(ip[stream] >= ilimit);
+            assert(ip[stream] >= ilowest);
         }
 #endif
         /* Compute olimit */
@@ -745,7 +744,7 @@ void HUF_decompress4X1_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs*
             /* Each iteration consumes up to 11 bits * 5 = 55 bits < 7 bytes
              * per stream.
              */
-            size_t const iiters = (size_t)(ip[0] - ilimit) / 7;
+            size_t const iiters = (size_t)(ip[0] - ilowest) / 7;
             /* We can safely run iters iterations before running bounds checks */
             size_t const iters = MIN(oiters, iiters);
             size_t const symbols = iters * 5;
@@ -756,8 +755,8 @@ void HUF_decompress4X1_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs*
              */
             olimit = op[3] + symbols;
 
-            /* Exit fast decoding loop once we get close to the end. */
-            if (op[3] + 20 > olimit)
+            /* Exit fast decoding loop once we reach the end. */
+            if (op[3] == olimit)
                 break;
 
             /* Exit the decoding loop if any input pointer has crossed the
@@ -836,7 +835,7 @@ HUF_decompress4X1_usingDTable_internal_fast(
     HUF_DecompressFastLoopFn loopFn)
 {
     void const* dt = DTable + 1;
-    const BYTE* const iend = (const BYTE*)cSrc + 6;
+    BYTE const* const ilowest = (BYTE const*)cSrc;
     BYTE* const oend = ZSTD_maybeNullPtrAdd((BYTE*)dst, dstSize);
     HUF_DecompressFastArgs args;
     {   size_t const ret = HUF_DecompressFastArgs_init(&args, dst, dstSize, cSrc, cSrcSize, DTable);
@@ -845,18 +844,22 @@ HUF_decompress4X1_usingDTable_internal_fast(
             return 0;
     }
 
-    assert(args.ip[0] >= args.ilimit);
+    assert(args.ip[0] >= args.ilowest);
     loopFn(&args);
 
-    /* Our loop guarantees that ip[] >= ilimit and that we haven't
+    /* Our loop guarantees that ip[] >= ilowest and that we haven't
     * overwritten any op[].
     */
-    assert(args.ip[0] >= iend);
-    assert(args.ip[1] >= iend);
-    assert(args.ip[2] >= iend);
-    assert(args.ip[3] >= iend);
+    assert(args.ip[0] >= ilowest);
+    assert(args.ip[0] >= ilowest);
+    assert(args.ip[1] >= ilowest);
+    assert(args.ip[2] >= ilowest);
+    assert(args.ip[3] >= ilowest);
     assert(args.op[3] <= oend);
-    (void)iend;
+
+    assert(ilowest == args.ilowest);
+    assert(ilowest + 6 == args.iend[0]);
+    (void)ilowest;
 
     /* finish bit streams one by one. */
     {   size_t const segmentSize = (dstSize+3) / 4;
@@ -1512,7 +1515,7 @@ void HUF_decompress4X2_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs*
     BYTE* op[4];
     BYTE* oend[4];
     HUF_DEltX2 const* const dtable = (HUF_DEltX2 const*)args->dt;
-    BYTE const* const ilimit = args->ilimit;
+    BYTE const* const ilowest = args->ilowest;
 
     /* Copy the arguments to local registers. */
     ZSTD_memcpy(&bits, &args->bits, sizeof(bits));
@@ -1535,7 +1538,7 @@ void HUF_decompress4X2_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs*
 #ifndef NDEBUG
         for (stream = 0; stream < 4; ++stream) {
             assert(op[stream] <= oend[stream]);
-            assert(ip[stream] >= ilimit);
+            assert(ip[stream] >= ilowest);
         }
 #endif
         /* Compute olimit */
@@ -1548,7 +1551,7 @@ void HUF_decompress4X2_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs*
              * We also know that each input pointer is >= ip[0]. So we can run
              * iters loops before running out of input.
              */
-            size_t iters = (size_t)(ip[0] - ilimit) / 7;
+            size_t iters = (size_t)(ip[0] - ilowest) / 7;
             /* Each iteration can produce up to 10 bytes of output per stream.
              * Each output stream my advance at different rates. So take the
              * minimum number of safe iterations among all the output streams.
@@ -1566,8 +1569,8 @@ void HUF_decompress4X2_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs*
              */
             olimit = op[3] + (iters * 5);
 
-            /* Exit the fast decoding loop if we are too close to the end. */
-            if (op[3] + 10 > olimit)
+            /* Exit the fast decoding loop once we reach the end. */
+            if (op[3] == olimit)
                 break;
 
             /* Exit the decoding loop if any input pointer has crossed the
@@ -1652,7 +1655,7 @@ HUF_decompress4X2_usingDTable_internal_fast(
     const HUF_DTable* DTable,
     HUF_DecompressFastLoopFn loopFn) {
     void const* dt = DTable + 1;
-    const BYTE* const iend = (const BYTE*)cSrc + 6;
+    const BYTE* const ilowest = (const BYTE*)cSrc;
     BYTE* const oend = ZSTD_maybeNullPtrAdd((BYTE*)dst, dstSize);
     HUF_DecompressFastArgs args;
     {
@@ -1662,16 +1665,19 @@ HUF_decompress4X2_usingDTable_internal_fast(
             return 0;
     }
 
-    assert(args.ip[0] >= args.ilimit);
+    assert(args.ip[0] >= args.ilowest);
     loopFn(&args);
 
     /* note : op4 already verified within main loop */
-    assert(args.ip[0] >= iend);
-    assert(args.ip[1] >= iend);
-    assert(args.ip[2] >= iend);
-    assert(args.ip[3] >= iend);
+    assert(args.ip[0] >= ilowest);
+    assert(args.ip[1] >= ilowest);
+    assert(args.ip[2] >= ilowest);
+    assert(args.ip[3] >= ilowest);
     assert(args.op[3] <= oend);
-    (void)iend;
+
+    assert(ilowest == args.ilowest);
+    assert(ilowest + 6 == args.iend[0]);
+    (void)ilowest;
 
     /* finish bitStreams one by one */
     {
diff --git a/lib/decompress/huf_decompress_amd64.S b/lib/decompress/huf_decompress_amd64.S
index 671624fe3..3b96b4461 100644
--- a/lib/decompress/huf_decompress_amd64.S
+++ b/lib/decompress/huf_decompress_amd64.S
@@ -131,7 +131,7 @@ HUF_decompress4X1_usingDTable_internal_fast_asm_loop:
     movq 88(%rax), %bits3
     movq 96(%rax), %dtable
     push %rax      /* argument */
-    push 104(%rax) /* ilimit */
+    push 104(%rax) /* ilowest */
     push 112(%rax) /* oend */
     push %olimit   /* olimit space */
 
@@ -156,11 +156,11 @@ HUF_decompress4X1_usingDTable_internal_fast_asm_loop:
     shrq $2, %r15
 
     movq %ip0,     %rax /* rax = ip0 */
-    movq 40(%rsp), %rdx /* rdx = ilimit */
-    subq %rdx,     %rax /* rax = ip0 - ilimit */
-    movq %rax,     %rbx /* rbx = ip0 - ilimit */
+    movq 40(%rsp), %rdx /* rdx = ilowest */
+    subq %rdx,     %rax /* rax = ip0 - ilowest */
+    movq %rax,     %rbx /* rbx = ip0 - ilowest */
 
-    /* rdx = (ip0 - ilimit) / 7 */
+    /* rdx = (ip0 - ilowest) / 7 */
     movabsq $2635249153387078803, %rdx
     mulq %rdx
     subq %rdx, %rbx
@@ -183,9 +183,8 @@ HUF_decompress4X1_usingDTable_internal_fast_asm_loop:
 
     /* If (op3 + 20 > olimit) */
     movq %op3, %rax    /* rax = op3 */
-    addq $20,  %rax    /* rax = op3 + 20 */
-    cmpq %rax, %olimit /* op3 + 20 > olimit */
-    jb .L_4X1_exit
+    cmpq %rax, %olimit /* op3 == olimit */
+    je .L_4X1_exit
 
     /* If (ip1 < ip0) go to exit */
     cmpq %ip0, %ip1
@@ -316,7 +315,7 @@ HUF_decompress4X1_usingDTable_internal_fast_asm_loop:
     /* Restore stack (oend & olimit) */
     pop %rax /* olimit */
     pop %rax /* oend */
-    pop %rax /* ilimit */
+    pop %rax /* ilowest */
     pop %rax /* arg */
 
     /* Save ip / op / bits */
@@ -387,7 +386,7 @@ HUF_decompress4X2_usingDTable_internal_fast_asm_loop:
     movq 96(%rax), %dtable
     push %rax      /* argument */
     push %rax      /* olimit */
-    push 104(%rax) /* ilimit */
+    push 104(%rax) /* ilowest */
 
     movq 112(%rax), %rax
     push %rax /* oend3 */
@@ -414,9 +413,9 @@ HUF_decompress4X2_usingDTable_internal_fast_asm_loop:
 
     /* We can consume up to 7 input bytes each iteration. */
     movq %ip0,     %rax  /* rax = ip0 */
-    movq 40(%rsp), %rdx  /* rdx = ilimit */
-    subq %rdx,     %rax  /* rax = ip0 - ilimit */
-    movq %rax,    %r15   /* r15 = ip0 - ilimit */
+    movq 40(%rsp), %rdx  /* rdx = ilowest */
+    subq %rdx,     %rax  /* rax = ip0 - ilowest */
+    movq %rax,    %r15   /* r15 = ip0 - ilowest */
 
     /* rdx = rax / 7 */
     movabsq $2635249153387078803, %rdx
@@ -426,7 +425,7 @@ HUF_decompress4X2_usingDTable_internal_fast_asm_loop:
     addq %r15, %rdx
     shrq $2, %rdx
 
-    /* r15 = (ip0 - ilimit) / 7 */
+    /* r15 = (ip0 - ilowest) / 7 */
     movq %rdx, %r15
 
     /* r15 = min(r15, min(oend0 - op0, oend1 - op1, oend2 - op2, oend3 - op3) / 10) */
@@ -467,9 +466,8 @@ HUF_decompress4X2_usingDTable_internal_fast_asm_loop:
 
     /* If (op3 + 10 > olimit) */
     movq %op3, %rax    /* rax = op3 */
-    addq $10,  %rax    /* rax = op3 + 10 */
-    cmpq %rax, %olimit /* op3 + 10 > olimit */
-    jb .L_4X2_exit
+    cmpq %rax, %olimit /* op3 == olimit */
+    je .L_4X2_exit
 
     /* If (ip1 < ip0) go to exit */
     cmpq %ip0, %ip1
@@ -537,7 +535,7 @@ HUF_decompress4X2_usingDTable_internal_fast_asm_loop:
     pop %rax /* oend1 */
     pop %rax /* oend2 */
     pop %rax /* oend3 */
-    pop %rax /* ilimit */
+    pop %rax /* ilowest */
     pop %rax /* olimit */
     pop %rax /* arg */