diff --git a/ChangeLog b/ChangeLog
index 1fa674b..a6fa98a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -55,6 +55,10 @@ a fixed maximum following a group that contains a subroutine reference was
 incorrectly compiled and could trigger buffer overflow. This bug was discovered 
 by the LLVM fuzzer.
 
+14. Negative relative recursive references such as (?-7) to non-existent 
+subpatterns were not being diagnosed and could lead to unpredictable behaviour. 
+This bug was discovered by the LLVM fuzzer.
+
 
 Version 10.10 06-March-2015
 ---------------------------
diff --git a/src/pcre2_compile.c b/src/pcre2_compile.c
index 2b04f08..4fee058 100644
--- a/src/pcre2_compile.c
+++ b/src/pcre2_compile.c
@@ -3179,15 +3179,15 @@ for (;; ptr++)
   BOOL xclass_has_prop;
 #endif
   int newoptions;
-  uint32_t recno;
-  int refsign;
+  int recno;                               /* Must be signed */
+  int refsign;                             /* Must be signed */
   int skipbytes;
-  uint32_t subreqcu, subfirstcu;
-  int32_t subreqcuflags, subfirstcuflags;
   int terminator;
   unsigned int mclength;
   unsigned int tempbracount;
   uint32_t ec;
+  uint32_t subreqcu, subfirstcu;
+  int32_t subreqcuflags, subfirstcuflags;  /* Must be signed */
   PCRE2_UCHAR mcbuffer[8];
 
   /* Get next character in the pattern */
@@ -5443,13 +5443,13 @@ for (;; ptr++)
             }
           if (refsign != 0) recno = (refsign == CHAR_MINUS)?
             cb->bracount - recno + 1 : recno + cb->bracount;
-          if (recno <= 0 || recno > cb->final_bracount)
+          if (recno <= 0 || (uint32_t)recno > cb->final_bracount)
             {
             *errorcodeptr = ERR15;
             goto FAILED;
             }
           PUT2(code, 2+LINK_SIZE, recno);
-          if (recno > cb->top_backref) cb->top_backref = recno;
+          if ((uint32_t)recno > cb->top_backref) cb->top_backref = recno;
           break;
           }
 
@@ -5475,7 +5475,7 @@ for (;; ptr++)
           for (;;)
             {
             recno = GET2(slot, 0);   /* Number for last found */
-            if (recno > cb->top_backref) cb->top_backref = recno;
+            if ((uint32_t)recno > cb->top_backref) cb->top_backref = recno;
             count++;
             if (++i >= cb->names_found) break;
             slot += cb->name_entry_size;
@@ -6000,7 +6000,7 @@ for (;; ptr++)
               open_capitem *oc;
               recno = GET2(slot, 0);
               cb->backref_map |= (recno < 32)? (1 << recno) : 1;
-              if (recno > cb->top_backref) cb->top_backref = recno;
+              if ((uint32_t)recno > cb->top_backref) cb->top_backref = recno;
 
               /* Check to see if this back reference is recursive, that it, it
               is inside the group that it references. A flag is set so that the
@@ -6121,7 +6121,7 @@ for (;; ptr++)
 
             if (called == NULL)
               {
-              if (recno > cb->final_bracount)
+              if ((uint32_t)recno > cb->final_bracount)
                 {
                 *errorcodeptr = ERR15;
                 goto FAILED;
@@ -6626,7 +6626,7 @@ for (;; ptr++)
         *code++ = ((options & PCRE2_CASELESS) != 0)? OP_REFI : OP_REF;
         PUT2INC(code, 0, recno);
         cb->backref_map |= (recno < 32)? (1 << recno) : 1;
-        if (recno > cb->top_backref) cb->top_backref = recno;
+        if ((uint32_t)recno > cb->top_backref) cb->top_backref = recno;
 
         /* Check to see if this back reference is recursive, that it, it
         is inside the group that it references. A flag is set so that the
diff --git a/testdata/testinput2 b/testdata/testinput2
index ead245a..eaa445c 100644
--- a/testdata/testinput2
+++ b/testdata/testinput2
@@ -4249,4 +4249,8 @@ a random value. /Ix
 
 "X((?2)()*+){2}"B
 
+/(?<=\bABQ(3(?-7)))/
+
+/(?<=\bABQ(3(?+7)))/
+
 # End of testinput2 
diff --git a/testdata/testoutput2 b/testdata/testoutput2
index fda5412..80bdadf 100644
--- a/testdata/testoutput2
+++ b/testdata/testoutput2
@@ -14251,4 +14251,10 @@ Failed: error 128 at offset 3: assertion expected after (?( or (?(?C)
         End
 ------------------------------------------------------------------
 
+/(?<=\bABQ(3(?-7)))/
+Failed: error 115 at offset 15: reference to non-existent subpattern
+
+/(?<=\bABQ(3(?+7)))/
+Failed: error 115 at offset 15: reference to non-existent subpattern
+
 # End of testinput2