diff --git a/src/ChangeLog b/src/ChangeLog
index d820d7f1b..2c215dce5 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2002-07-30  Pavel Roskin  <proski@gnu.org>
+
+	* ext.c (regex_command): Additional check to prevent reading
+	unallocated memory when matching "shell/".  Found by Valgrind.
+
 2002-07-29  Pavel Roskin  <proski@gnu.org>
 
 	* setup.c: Eliminate all PORT* macros.
diff --git a/src/ext.c b/src/ext.c
index 217df9e58..c624b5385 100644
--- a/src/ext.c
+++ b/src/ext.c
@@ -472,9 +472,9 @@ file as an example of how to write it.\n\
 	            found = 1;
 	    } else if (!strncmp (p, "shell/", 6)) {
 	        p += 6;
-	        if (*p == '.') {
-	            if (!strncmp (p, filename + file_len - (q - p),
-	                q - p))
+	        if (*p == '.' && file_len >= (q - p)) {
+	            if (file_len >= (q - p) &&
+			 !strncmp (p, filename + file_len - (q - p), q - p))
 	                found = 1;
 	        } else {
 	            if (q - p == file_len && !strncmp (p, filename, q - p))