diff --git a/src/pcre2_compile.c b/src/pcre2_compile.c
index b8291e415..d0ed393dd 100644
--- a/src/pcre2_compile.c
+++ b/src/pcre2_compile.c
@@ -11147,6 +11147,8 @@ an offset is available in the parsed pattern. */
 ptr = pattern + cb.erroroffset;
 
 HAD_EARLY_ERROR:
+PCRE2_ASSERT(ptr >= pattern); /* Ensure we don't return invalid erroroffset */
+PCRE2_ASSERT(ptr <= (pattern + patlen));
 *erroroffset = ptr - pattern;
 
 HAD_ERROR: