diff --git a/doc/pcre2api.3 b/doc/pcre2api.3
index 8eb0b68dc..2f5c70528 100644
--- a/doc/pcre2api.3
+++ b/doc/pcre2api.3
@@ -3815,9 +3815,10 @@ PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output buffer is
 too small. The default action is to return PCRE2_ERROR_NOMEMORY immediately. If
 this option is set, however, \fBpcre2_substitute()\fP continues to go through
 the motions of matching and substituting (without, of course, writing anything)
-in order to compute the size of buffer that is needed. This value is passed
-back via the \fIoutlengthptr\fP variable, with the result of the function still
-being PCRE2_ERROR_NOMEMORY.
+in order to compute the size of buffer that is needed, which will include the
+extra space for the terminating NUL. This value is passed back via the
+\fIoutlengthptr\fP variable, with the result of the function still being
+PCRE2_ERROR_NOMEMORY.
 .P
 Passing a buffer size of zero is a permitted way of finding out how much memory
 is needed for given substitution. However, this does mean that the entire
@@ -3938,7 +3939,7 @@ that can be applied to group captures. For example, if group 1 has captured
 .P
 If either PCRE2_UTF or PCRE2_UCP was set when the pattern was compiled, Unicode
 properties are used for case forcing characters whose code points are greater
-than 127. However, only basic case folding, as determined by the Unicode file
+than 127. However, only simple case folding, as determined by the Unicode file
 \fBCaseFolding.txt\fP is supported. PCRE2 does not support language-specific
 special casing rules such as using different lower case Greek sigmas in the
 middle and ends of words (as defined in the Unicode file
diff --git a/doc/pcre2test.1 b/doc/pcre2test.1
index 73845f65b..db385c865 100644
--- a/doc/pcre2test.1
+++ b/doc/pcre2test.1
@@ -1225,7 +1225,7 @@ command are of two types.
 The following modifiers set options for \fBpcre2_match()\fP or
 \fBpcre2_dfa_match()\fP. See
 .\" HREF
-\fBpcreapi\fP
+\fBpcre2api\fP
 .\"
 for a description of their effects.
 .sp
diff --git a/src/pcre2_compile.c b/src/pcre2_compile.c
index caf34a66f..c439b495b 100644
--- a/src/pcre2_compile.c
+++ b/src/pcre2_compile.c
@@ -826,12 +826,12 @@ for (;;)
     return;
 
     case META_CAPTURE:
-    fprintf(stderr, "META_CAPTURE %d", meta_arg);
+    fprintf(stderr, "META_CAPTURE %u", meta_arg);
     break;
 
     case META_RECURSE:
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "META_RECURSE %d %zd", meta_arg, offset);
+    fprintf(stderr, "META_RECURSE %u %zu", meta_arg, offset);
     break;
 
     case META_BACKREF:
@@ -839,7 +839,7 @@ for (;;)
       offset = cb->small_ref_offset[meta_arg];
     else
       GETOFFSET(offset, pptr);
-    fprintf(stderr, "META_BACKREF %d %zd", meta_arg, offset);
+    fprintf(stderr, "META_BACKREF %u %zu", meta_arg, offset);
     break;
 
     case META_ESCAPE:
@@ -847,7 +847,7 @@ for (;;)
       {
       uint32_t ptype = *pptr >> 16;
       uint32_t pvalue = *pptr++ & 0xffff;
-      fprintf(stderr, "META \\%c %d %d", (meta_arg == ESC_P)? CHAR_P:CHAR_p,
+      fprintf(stderr, "META \\%c %u %u", (meta_arg == ESC_P)? CHAR_P:CHAR_p,
         ptype, pvalue);
       }
     else
@@ -914,7 +914,7 @@ for (;;)
     case META_LOOKAHEAD_NA: fprintf(stderr, "META (*napla:"); break;
     case META_SCRIPT_RUN: fprintf(stderr, "META (*sr:"); break;
     case META_KET: fprintf(stderr, "META )"); break;
-    case META_ALT: fprintf(stderr, "META | %d", meta_arg); break;
+    case META_ALT: fprintf(stderr, "META | %u", meta_arg); break;
 
     case META_CLASS: fprintf(stderr, "META ["); break;
     case META_CLASS_NOT: fprintf(stderr, "META [^"); break;
@@ -925,8 +925,8 @@ for (;;)
     case META_RANGE_LITERAL: fprintf(stderr, "META - (literal)"); break;
     case META_RANGE_ESCAPED: fprintf(stderr, "META - (escaped)"); break;
 
-    case META_POSIX: fprintf(stderr, "META_POSIX %d", *pptr++); break;
-    case META_POSIX_NEG: fprintf(stderr, "META_POSIX_NEG %d", *pptr++); break;
+    case META_POSIX: fprintf(stderr, "META_POSIX %u", *pptr++); break;
+    case META_POSIX_NEG: fprintf(stderr, "META_POSIX_NEG %u", *pptr++); break;
 
     case META_ACCEPT: fprintf(stderr, "META (*ACCEPT)"); break;
     case META_FAIL: fprintf(stderr, "META (*FAIL)"); break;
@@ -941,22 +941,22 @@ for (;;)
     break;
 
     case META_LOOKBEHIND:
-    fprintf(stderr, "META (?<= %d %d", meta_arg, *pptr);
+    fprintf(stderr, "META (?<= %u %u", meta_arg, *pptr);
     pptr += 2;
     break;
 
     case META_LOOKBEHIND_NA:
-    fprintf(stderr, "META (*naplb: %d %d", meta_arg, *pptr);
+    fprintf(stderr, "META (*naplb: %u %u", meta_arg, *pptr);
     pptr += 2;
     break;
 
     case META_LOOKBEHINDNOT:
-    fprintf(stderr, "META (?<! %d %d", meta_arg, *pptr);
+    fprintf(stderr, "META (?<! %u %u", meta_arg, *pptr);
     pptr += 2;
     break;
 
     case META_CALLOUT_NUMBER:
-    fprintf(stderr, "META (?C%d) next=%d/%d", pptr[2], pptr[0],
+    fprintf(stderr, "META (?C%u) next=%u/%u", pptr[2], pptr[0],
        pptr[1]);
     pptr += 3;
     break;
@@ -965,86 +965,86 @@ for (;;)
       {
       uint32_t patoffset = *pptr++;    /* Offset of next pattern item */
       uint32_t patlength = *pptr++;    /* Length of next pattern item */
-      fprintf(stderr, "META (?Cstring) length=%d offset=", *pptr++);
+      fprintf(stderr, "META (?Cstring) length=%u offset=", *pptr++);
       GETOFFSET(offset, pptr);
-      fprintf(stderr, "%zd next=%d/%d", offset, patoffset, patlength);
+      fprintf(stderr, "%zu next=%u/%u", offset, patoffset, patlength);
       }
     break;
 
     case META_RECURSE_BYNAME:
-    fprintf(stderr, "META (?(&name) length=%d offset=", *pptr++);
+    fprintf(stderr, "META (?(&name) length=%u offset=", *pptr++);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     break;
 
     case META_BACKREF_BYNAME:
-    fprintf(stderr, "META_BACKREF_BYNAME length=%d offset=", *pptr++);
+    fprintf(stderr, "META_BACKREF_BYNAME length=%u offset=", *pptr++);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     break;
 
     case META_COND_NUMBER:
-    fprintf(stderr, "META_COND_NUMBER %d offset=", pptr[SIZEOFFSET]);
+    fprintf(stderr, "META_COND_NUMBER %u offset=", pptr[SIZEOFFSET]);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     pptr++;
     break;
 
     case META_COND_DEFINE:
     fprintf(stderr, "META (?(DEFINE) offset=");
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     break;
 
     case META_COND_VERSION:
     fprintf(stderr, "META (?(VERSION%s", (*pptr++ == 0)? "=" : ">=");
-    fprintf(stderr, "%d.", *pptr++);
-    fprintf(stderr, "%d)", *pptr++);
+    fprintf(stderr, "%u.", *pptr++);
+    fprintf(stderr, "%u)", *pptr++);
     break;
 
     case META_COND_NAME:
-    fprintf(stderr, "META (?(<name>) length=%d offset=", *pptr++);
+    fprintf(stderr, "META (?(<name>) length=%u offset=", *pptr++);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     break;
 
     case META_COND_RNAME:
-    fprintf(stderr, "META (?(R&name) length=%d offset=", *pptr++);
+    fprintf(stderr, "META (?(R&name) length=%u offset=", *pptr++);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     break;
 
     /* This is kept as a name, because it might be. */
 
     case META_COND_RNUMBER:
-    fprintf(stderr, "META (?(Rnumber) length=%d offset=", *pptr++);
+    fprintf(stderr, "META (?(Rnumber) length=%u offset=", *pptr++);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     break;
 
     case META_SCS_NAME:
-    fprintf(stderr, "META (*scan_substring:(<name>) length=%d offset=", *pptr++);
+    fprintf(stderr, "META (*scan_substring:(<name>) length=%u offset=", *pptr++);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     break;
 
     case META_SCS_NUMBER:
-    fprintf(stderr, "META_SCS_NUMBER %d offset=", pptr[SIZEOFFSET]);
+    fprintf(stderr, "META_SCS_NUMBER %u offset=", pptr[SIZEOFFSET]);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     pptr++;
     break;
 
     case META_SCS_NEXT_NAME:
-    fprintf(stderr, "META_SCS_NEXT_NAME length=%d offset=", *pptr++);
+    fprintf(stderr, "META_SCS_NEXT_NAME length=%u offset=", *pptr++);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     break;
 
     case META_SCS_NEXT_NUMBER:
-    fprintf(stderr, "META_SCS_NEXT_NUMBER %d offset=", pptr[SIZEOFFSET]);
+    fprintf(stderr, "META_SCS_NEXT_NUMBER %u offset=", pptr[SIZEOFFSET]);
     GETOFFSET(offset, pptr);
-    fprintf(stderr, "%zd", offset);
+    fprintf(stderr, "%zu", offset);
     pptr++;
     break;
 
@@ -1099,7 +1099,6 @@ associated JIT data. */
 PCRE2_EXP_DEFN pcre2_code * PCRE2_CALL_CONVENTION
 pcre2_code_copy(const pcre2_code *code)
 {
-PCRE2_SIZE *ref_count;
 pcre2_code *newcode;
 
 if (code == NULL) return NULL;
@@ -1113,7 +1112,7 @@ in the decoded tables. */
 
 if ((code->flags & PCRE2_DEREF_TABLES) != 0)
   {
-  ref_count = (PCRE2_SIZE *)(code->tables + TABLES_LENGTH);
+  PCRE2_SIZE *ref_count = (PCRE2_SIZE *)(code->tables + TABLES_LENGTH);
   (*ref_count)++;
   }
 
@@ -2597,9 +2596,7 @@ won't be recognized. */
     }
 
   while (ptr < ptrend && MAX_255(*ptr) && (cb->ctypes[*ptr] & ctype_word) != 0)
-    {
     ptr++;
-    }
   }
 
 /* Check name length */
@@ -5479,7 +5476,7 @@ static BOOL
 find_dupname_details(PCRE2_SPTR name, uint32_t length, int *indexptr,
   int *countptr, int *errorcodeptr, compile_block *cb)
 {
-uint32_t i, groupnumber;
+uint32_t i;
 int count;
 PCRE2_UCHAR *slot = cb->name_table;
 
@@ -5511,8 +5508,9 @@ count = 0;
 
 for (;;)
   {
+  uint32_t groupnumber = GET2(slot,0);
+
   count++;
-  groupnumber = GET2(slot,0);
   cb->backref_map |= (groupnumber < 32)? (1u << groupnumber) : 1;
   if (groupnumber > cb->top_backref) cb->top_backref = groupnumber;
   if (++i >= cb->names_found) break;
@@ -6800,7 +6798,7 @@ for (;; pptr++)
 #ifdef MAYBE_UTF_MULTI
       if (utf && NOT_FIRSTCU(code[-1]))
         {
-        PCRE2_UCHAR *lastchar = code - 1;
+        PCRE2_SPTR lastchar = code - 1;
         BACKCHAR(lastchar);
         mclength = (uint32_t)(code - lastchar);   /* Length of UTF character */
         memcpy(mcbuffer, lastchar, CU2BYTES(mclength));  /* Save the char */
@@ -7940,7 +7938,6 @@ PCRE2_UCHAR *last_branch = code;
 PCRE2_UCHAR *start_bracket = code;
 BOOL lookbehind;
 open_capitem capitem;
-int capnumber = 0;
 int okreturn = 1;
 uint32_t *pptr = *pptrptr;
 uint32_t firstcu, reqcu;
@@ -7998,7 +7995,7 @@ OP_SCBRAPOS, happens later, after the group has been compiled. */
 
 if (*code == OP_CBRA)
   {
-  capnumber = GET2(code, 1 + LINK_SIZE);
+  int capnumber = GET2(code, 1 + LINK_SIZE);
   capitem.number = capnumber;
   capitem.next = open_caps;
   capitem.assert_depth = cb->assert_depth;
@@ -10212,11 +10209,9 @@ show_parsed(&cb);
 #ifdef DEBUG_SHOW_CAPTURES
   {
   named_group *ng = cb.named_groups;
-  fprintf(stderr, "+++Captures: %d\n", cb.bracount);
+  fprintf(stderr, "+++Captures: %u\n", cb.bracount);
   for (i = 0; i < cb.names_found; i++, ng++)
-    {
-    fprintf(stderr, "+++%3d %.*s\n", ng->number, ng->length, ng->name);
-    }
+    fprintf(stderr, "+++%3u %.*s\n", ng->number, ng->length, ng->name);
   }
 #endif
 
@@ -10415,11 +10410,11 @@ if (errorcode == 0 && cb.had_recurse)
        rcode != NULL;
        rcode = find_recurse(rcode + 1 + LINK_SIZE, utf))
     {
-    int p, groupnumber;
+    int groupnumber = (int)GET(rcode, 1);
 
-    groupnumber = (int)GET(rcode, 1);
     if (groupnumber == 0) rgroup = codestart; else
       {
+      int p;
       PCRE2_SPTR search_from = codestart;
       rgroup = NULL;
       for (i = 0, p = start; i < ccount; i++, p = (p + 1) & 7)
diff --git a/src/pcre2_substitute.c b/src/pcre2_substitute.c
index fa9fe4450..9125d40f8 100644
--- a/src/pcre2_substitute.c
+++ b/src/pcre2_substitute.c
@@ -289,13 +289,14 @@ Returns:          >= 0 number of substitutions made
 overflow, either give an error immediately, or keep on, accumulating the
 length. */
 
-#define CHECKMEMCPY(from,length) \
+#define CHECKMEMCPY(from,length) do \
   { \
   if (!overflowed && lengthleft < length) \
     { \
     if ((suboptions & PCRE2_SUBSTITUTE_OVERFLOW_LENGTH) == 0) goto NOROOM; \
     overflowed = TRUE; \
     extra_needed = length - lengthleft; \
+    lengthleft = 0; \
     } \
   else if (overflowed) \
     { \
@@ -307,7 +308,7 @@ length. */
     buff_offset += length; \
     lengthleft -= length; \
     } \
-  }
+  } while (0)
 
 /* Here's the function */
 
@@ -439,8 +440,7 @@ if (subject == NULL)
 
 /* Find length of zero-terminated subject */
 
-if (length == PCRE2_ZERO_TERMINATED)
-  length = subject? PRIV(strlen)(subject) : 0;
+if (length == PCRE2_ZERO_TERMINATED) length = PRIV(strlen)(subject);
 
 /* Check UTF replacement string if necessary. */
 
@@ -597,9 +597,7 @@ do
 
   ptr = replacement;
   if ((suboptions & PCRE2_SUBSTITUTE_LITERAL) != 0)
-    {
     CHECKMEMCPY(ptr, rlength);
-    }
 
   /* Within a non-literal replacement, which must be scanned character by
   character, local literal mode can be set by \Q, but only in extended mode
@@ -942,7 +940,7 @@ do
           GETCHARINCTEST(ch, subptr);
           if (forcecase != 0)
             {
-            if (mcontext->substitute_case_callout)
+            if (mcontext != NULL && mcontext->substitute_case_callout != NULL)
               {
               ch = mcontext->substitute_case_callout(
                 ch,
@@ -1104,7 +1102,7 @@ do
       LITERAL:
       if (forcecase != 0)
         {
-        if (mcontext->substitute_case_callout)
+        if (mcontext != NULL && mcontext->substitute_case_callout != NULL)
           {
           ch = mcontext->substitute_case_callout(
             ch,
@@ -1194,8 +1192,17 @@ if (!replacement_only)
   CHECKMEMCPY(subject + start_offset, fraglength);
   }
 
-temp[0] = 0;
-CHECKMEMCPY(temp, 1);
+/* Zero terminate the output string, truncating if needed. */
+
+if (lengthleft-- > 0) ++buff_offset;
+else
+  {
+  if ((suboptions & PCRE2_SUBSTITUTE_OVERFLOW_LENGTH) == 0) goto NOROOM;
+  overflowed = TRUE;
+  extra_needed++;
+  lengthleft = 0;
+  }
+if (!overflowed || lengthleft == 0) buffer[buff_offset] = 0; else extra_needed++;
 
 /* If overflowed is set it means the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set,
 and matching has carried on after a full buffer, in order to compute the length
@@ -1222,6 +1229,7 @@ if (internal_match_data != NULL) pcre2_match_data_free(internal_match_data);
 return rc;
 
 NOROOM:
+buffer[buff_offset] = 0;
 rc = PCRE2_ERROR_NOMEMORY;
 goto EXIT;
 
diff --git a/src/pcre2test.c b/src/pcre2test.c
index 7f01cf928..a241aba43 100644
--- a/src/pcre2test.c
+++ b/src/pcre2test.c
@@ -7500,6 +7500,13 @@ if (pat_patctl.replacement[0] != 0)
     return PR_OK;
     }
 
+  if (pat_patctl.replacement_case[0] != 0 &&
+      (dat_datctl.control & CTL_NULLCONTEXT) != 0)
+    {
+    fprintf(outfile, "** Replacement case callouts are not supported with null_context.\n");
+    return PR_OK;
+    }
+
   if ((dat_datctl.control & CTL_ALLCAPTURES) != 0)
     fprintf(outfile, "** Ignored with replacement text: allcaptures\n");
   }
diff --git a/testdata/testinput2 b/testdata/testinput2
index 1fbb778e0..45c8c909f 100644
--- a/testdata/testinput2
+++ b/testdata/testinput2
@@ -4220,6 +4220,37 @@
     apple lemon blackberry
 
 /abc/
+    123abc123\=replace=XYZ
+    123abc123\=replace=[10]XYZ
+\= Expect error
+    123abc123\=replace=[9]XYZ
+    123abc123\=substitute_overflow_length,replace=[9]XYZ
+    123abc123\=substitute_overflow_length,replace=[6]XYZ
+    123abc123\=substitute_overflow_length,replace=[1]XYZ
+    123abc123\=substitute_overflow_length,replace=[0]XYZ
+
+/abc/
+    123abc123\=replace=XY
+    123abc123\=replace=[9]XY
+    123abc123\=replace=[9]XY,substitute_literal
+\= Expect error
+    123abc123\=replace=[8]XY,substitute_overflow_length
+    123abc123\=replace=[8]XY,substitute_overflow_length,substitute_literal
+    123abc123\=replace=[6]XY,substitute_overflow_length
+    123abc123\=replace=[6]XY,substitute_overflow_length,substitute_literal
+    123abc123\=replace=[5]XY,substitute_overflow_length
+    123abc123\=replace=[5]XY,substitute_overflow_length,substitute_literal
+    123abc123\=replace=[4]XY,substitute_overflow_length
+    123abc123\=replace=[4]XY,substitute_overflow_length,substitute_literal
+    123abc123\=replace=[3]XY,substitute_overflow_length
+    123abc123\=replace=[3]XY,substitute_overflow_length,substitute_literal
+    123abc123\=replace=[2]XY,substitute_overflow_length
+    123abc123\=replace=[2]XY,substitute_overflow_length,substitute_literal
+
+/abc/substitute_literal
+    123abc123\=replace=XYZ
+    123abc123\=replace=[10]XYZ
+\= Expect error
     123abc123\=replace=[9]XYZ
     123abc123\=substitute_overflow_length,replace=[9]XYZ
     123abc123\=substitute_overflow_length,replace=[6]XYZ
@@ -4714,7 +4745,7 @@ B)x/alt_verbnames,mark
 
 /abcd/null_context
     abcd\=null_context
-\= Expect error - not allowed together
+\= Expect not allowed together
     abcd\=null_context,find_limits
     abcd\=allusedtext,startchar
 
@@ -6061,6 +6092,8 @@ a)"xI
 
 /abc/replace=\U$0,substitute_extended,substitute_case_callout=a.U.b.V.
     XabcY
+\= Expect not supported
+    XabcY\=null_context
 
 /a/substitute_extended
     XaY\=replace=\U$0,substitute_case_callout=a.U.
diff --git a/testdata/testoutput2 b/testdata/testoutput2
index 99714596e..6e671d1ad 100644
--- a/testdata/testoutput2
+++ b/testdata/testoutput2
@@ -13884,6 +13884,61 @@ Failed: error -48: no more memory: 23 code units are needed
  1: fruit\x00juice lemon blackberry
 
 /abc/
+    123abc123\=replace=XYZ
+ 1: 123XYZ123
+    123abc123\=replace=[10]XYZ
+ 1: 123XYZ123
+\= Expect error
+    123abc123\=replace=[9]XYZ
+Failed: error -48: no more memory
+    123abc123\=substitute_overflow_length,replace=[9]XYZ
+Failed: error -48: no more memory: 10 code units are needed
+    123abc123\=substitute_overflow_length,replace=[6]XYZ
+Failed: error -48: no more memory: 10 code units are needed
+    123abc123\=substitute_overflow_length,replace=[1]XYZ
+Failed: error -48: no more memory: 10 code units are needed
+    123abc123\=substitute_overflow_length,replace=[0]XYZ
+Failed: error -48: no more memory: 10 code units are needed
+
+/abc/
+    123abc123\=replace=XY
+ 1: 123XY123
+    123abc123\=replace=[9]XY
+ 1: 123XY123
+    123abc123\=replace=[9]XY,substitute_literal
+ 1: 123XY123
+\= Expect error
+    123abc123\=replace=[8]XY,substitute_overflow_length
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[8]XY,substitute_overflow_length,substitute_literal
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[6]XY,substitute_overflow_length
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[6]XY,substitute_overflow_length,substitute_literal
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[5]XY,substitute_overflow_length
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[5]XY,substitute_overflow_length,substitute_literal
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[4]XY,substitute_overflow_length
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[4]XY,substitute_overflow_length,substitute_literal
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[3]XY,substitute_overflow_length
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[3]XY,substitute_overflow_length,substitute_literal
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[2]XY,substitute_overflow_length
+Failed: error -48: no more memory: 9 code units are needed
+    123abc123\=replace=[2]XY,substitute_overflow_length,substitute_literal
+Failed: error -48: no more memory: 9 code units are needed
+
+/abc/substitute_literal
+    123abc123\=replace=XYZ
+ 1: 123XYZ123
+    123abc123\=replace=[10]XYZ
+ 1: 123XYZ123
+\= Expect error
     123abc123\=replace=[9]XYZ
 Failed: error -48: no more memory
     123abc123\=substitute_overflow_length,replace=[9]XYZ
@@ -15131,7 +15186,7 @@ No match
 /abcd/null_context
     abcd\=null_context
  0: abcd
-\= Expect error - not allowed together
+\= Expect not allowed together
     abcd\=null_context,find_limits
 ** Not allowed together: find_limits null_context
     abcd\=allusedtext,startchar
@@ -18065,6 +18120,9 @@ Failed: error -55 at offset 3 in replacement: requested value is not set
 /abc/replace=\U$0,substitute_extended,substitute_case_callout=a.U.b.V.
     XabcY
  1: XUVcY
+\= Expect not supported
+    XabcY\=null_context
+** Replacement case callouts are not supported with null_context.
 
 /a/substitute_extended
     XaY\=replace=\U$0,substitute_case_callout=a.U.