diff --git a/src/test/data/script_tests.json b/src/test/data/script_tests.json
--- a/src/test/data/script_tests.json
+++ b/src/test/data/script_tests.json
@@ -897,8 +897,16 @@
 ["-42 521", "NUM2BIN", "P2SH,STRICTENC,MONOLITH_OPCODES", "PUSH_SIZE", "Pushing 521 bytes is not"],
 ["-42 -3", "NUM2BIN", "P2SH,STRICTENC,MONOLITH_OPCODES", "PUSH_SIZE", "Negative size"],
 ["0x05 0xabcdef4280 4", "NUM2BIN 0x04 0xabcdefc2 EQUAL", "P2SH,STRICTENC,MONOLITH_OPCODES", "OK", "Item size reduction"],
+["0x03 0xabcdef 2", "NUM2BIN", "P2SH,STRICTENC,MONOLITH_OPCODES", "IMPOSSIBLE_ENCODING", "output too small"],
 ["0x01 0x80 0", "NUM2BIN 0 EQUAL", "P2SH,STRICTENC,MONOLITH_OPCODES", "OK", "Negative zero"],
 ["0x01 0x80 3", "NUM2BIN 0x03 0x000000 EQUAL", "P2SH,STRICTENC,MONOLITH_OPCODES", "OK", "Negative zero, larger output"],
+["0x05 0xabcdef4243 5", "NUM2BIN 0x05 0xabcdef4243 EQUAL", "P2SH,STRICTENC,MONOLITH_OPCODES", "OK", "NUM2BIN where len(a) > 4"],
+["0x05 0xabcdef4243 6", "NUM2BIN 0x06 0xabcdef424300 EQUAL", "P2SH,STRICTENC,MONOLITH_OPCODES", "OK", "pads output properly"],
+["0x05 0xabcdef4243 4", "NUM2BIN", "P2SH,STRICTENC,MONOLITH_OPCODES", "IMPOSSIBLE_ENCODING", "output too small"],
+["0x10 0x0102030405060708090A0B0C0D0E0F10 DUP CAT DUP CAT DUP CAT DUP CAT DUP CAT 0x08 0x0102030405060708 CAT DUP 520", "NUM2BIN EQUAL", "P2SH,STRICTENC,MONOLITH_OPCODES", "OK", "520 byte 1st operand"],
+["0x05 0x0000000000 5", "NUM2BIN 0x05 0x0000000000 EQUAL", "P2SH,STRICTENC,MONOLITH_OPCODES", "OK", "1st operand not minimally encoded"],
+["1 0x05 0x0500000000", "NUM2BIN", "P2SH,STRICTENC,MONOLITH_OPCODES", "UNKNOWN_ERROR", "2nd operand not minimally encoded"],
+["0x04 0xabcdef42 0x05 0xabcdef4243", "NUM2BIN", "P2SH,STRICTENC,MONOLITH_OPCODES", "UNKNOWN_ERROR", "2nd operand > 4 bytes"],
 
 ["BIN2NUM"],
 ["", "BIN2NUM 0 EQUAL", "P2SH,STRICTENC,MONOLITH_OPCODES", "INVALID_STACK_OPERATION", "BIN2NUM, empty stack"],
diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp
--- a/src/test/script_tests.cpp
+++ b/src/test/script_tests.cpp
@@ -55,6 +55,7 @@
     {SCRIPT_ERR_PUBKEY_COUNT, "PUBKEY_COUNT"},
     {SCRIPT_ERR_INVALID_OPERAND_SIZE, "OPERAND_SIZE"},
     {SCRIPT_ERR_INVALID_NUMBER_RANGE, "INVALID_NUMBER_RANGE"},
+    {SCRIPT_ERR_IMPOSSIBLE_ENCODING, "IMPOSSIBLE_ENCODING"},
     {SCRIPT_ERR_INVALID_SPLIT_RANGE, "SPLIT_RANGE"},
     {SCRIPT_ERR_VERIFY, "VERIFY"},
     {SCRIPT_ERR_EQUALVERIFY, "EQUALVERIFY"},