diff --git a/libcob/ChangeLog b/libcob/ChangeLog
index 3f523717..e6f111a6 100644
--- a/libcob/ChangeLog
+++ b/libcob/ChangeLog
@@ -1,4 +1,9 @@
 
+2024-12-20  David Declerck <david.declerck@ocamlpro.com>
+
+	* fileio.c (indexed_start_internal): improve handling of partial
+	  keys, to ensure BDB always compares keys of identical length
+
 2024-12-18  David Declerck <david.declerck@ocamlpro.com>
 
 	* string.c: fix a bug where the source of STRING/UNSTRING/INSPECT
diff --git a/libcob/fileio.c b/libcob/fileio.c
index df7cc89c..26cde85a 100644
--- a/libcob/fileio.c
+++ b/libcob/fileio.c
@@ -923,6 +923,9 @@ bdb_bt_compare (DB *db, const DBT *k1, const DBT *k2
 {
 	const unsigned char *col = (unsigned char *)DBT_GET_APP_DATA (k1);
 	COB_UNUSED (db);
+#if DB_VERSION_MAJOR >= 6
+	locp = NULL;	/* docs: must be set to NULL or corruption can occur ... */
+#endif
 #ifdef USE_BDB_KEYDIFF /* flag passed with CPPFLAGS */
 	return cob_cmp_strings (k1->data, k2->data, (size_t)k1->size, (size_t)k2->size, col);
 #else
@@ -936,9 +939,6 @@ bdb_bt_compare (DB *db, const DBT *k1, const DBT *k2
 		cob_hard_failure ();
 	}
 	/* LCOV_EXCL_STOP */
-#if DB_VERSION_MAJOR >= 6
-	locp = NULL;	/* docs: must be set to NULL or corruption can occur ... */
-#endif
 	return indexed_key_compare (k1->data, k2->data, k2->size, col);
 #endif /* USE_BDB_KEYDIFF */
 }
@@ -3909,7 +3909,10 @@ indexed_start_internal (cob_file *f, const int cond, cob_field *key,
 
 	/* Search */
 	bdb_setkey (f, p->key_index);
-	p->key.size = (cob_dbtsize_t)partlen;		/* may be partial key */
+	if (partlen < fullkeylen) {
+		memset((char *)p->key.data + partlen, 0, fullkeylen - partlen);
+	}
+
 	/* The open cursor makes this function atomic */
 	if (p->key_index != 0) {
 		p->db[0]->cursor (p->db[0], NULL, &p->cursor[0], 0);
diff --git a/tests/testsuite.src/run_file.at b/tests/testsuite.src/run_file.at
index 9dca167e..6d97f578 100644
--- a/tests/testsuite.src/run_file.at
+++ b/tests/testsuite.src/run_file.at
@@ -3098,6 +3098,64 @@ rewriting key: 98651234
 AT_CLEANUP
 
 
+AT_SETUP([INDEXED START with partial key and collating sequence])
+AT_KEYWORDS([runfile READ WRITE START])
+
+AT_DATA([prog.cob], [
+       IDENTIFICATION DIVISION.
+       PROGRAM-ID. prog.
+       ENVIRONMENT DIVISION.
+       INPUT-OUTPUT SECTION.
+       FILE-CONTROL.
+           SELECT F-DATA ASSIGN TO EXTERNAL fdata
+             ORGANIZATION INDEXED
+             ACCESS MODE DYNAMIC
+             RECORD KEY R-KEY
+             FILE STATUS F-STATUS.
+       DATA DIVISION.
+       FILE SECTION.
+       FD F-DATA.
+       01 R-DATA.
+         05 R-KEY.
+           10 R-SUBKEY-1  PIC X(3).
+           10 R-SUBKEY-2  PIC X(2).
+         05 R-NUM         PIC 99.
+       WORKING-STORAGE SECTION.
+       01 F-STATUS  PIC X(2)  VALUE SPACE.
+       PROCEDURE DIVISION.
+           OPEN OUTPUT F-DATA.
+           MOVE "ABC12" TO R-KEY.
+           MOVE 1 TO R-NUM.
+           WRITE R-DATA.
+           MOVE "DEF34" TO R-KEY.
+           MOVE 2 TO R-NUM.
+           WRITE R-DATA.
+           MOVE "GHI56" TO R-KEY.
+           MOVE 3 TO R-NUM.
+           WRITE R-DATA.
+           CLOSE F-DATA.
+           OPEN INPUT F-DATA.
+           MOVE SPACES TO R-KEY.
+           MOVE "DEF" TO R-SUBKEY-1.
+           START F-DATA KEY >= R-SUBKEY-1.
+           DISPLAY "START STATUS: " F-STATUS.
+           READ F-DATA NEXT.
+           DISPLAY "READ STATUS: " F-STATUS.
+           DISPLAY "READ " R-KEY ", " R-NUM.
+           CLOSE F-DATA.
+           STOP RUN.
+])
+
+AT_CHECK([$COMPILE -fdefault-file-colseq=EBCDIC prog.cob], [0], [], [])
+AT_CHECK([$COBCRUN_DIRECT ./prog], [0],
+[START STATUS: 00
+READ STATUS: 00
+READ DEF34, 02
+], [])
+
+AT_CLEANUP
+
+
 AT_SETUP([WRITE + REWRITE FILE name])
 AT_KEYWORDS([runfile RELATIVE COB_SYNC])