diff --git a/tools/mpy_ld.py b/tools/mpy_ld.py
index 87e57869f6..4f37b0f71a 100755
--- a/tools/mpy_ld.py
+++ b/tools/mpy_ld.py
@@ -89,8 +89,17 @@ def asm_jump_x86(entry):
 def asm_jump_thumb(entry):
     # Only signed values that fit in 12 bits are supported
     b_off = entry - 4
-    assert b_off >> 11 == 0 or b_off >> 11 == -1, b_off
-    return struct.pack("<H", 0xE000 | (b_off >> 1 & 0x07FF))
+    if b_off >> 11 == 0 or b_off >> 11 == -1:
+        return struct.pack("<H", 0xE000 | (b_off >> 1 & 0x07FF))
+    else:
+        # Use BL instruction
+        # Two 16-bit instructions in sequence
+        # each on form: 1111 HOOO OOOO OOOO
+        # first instruction has H=0, and has high 11 bits of the Offset
+        # second instruction has H=1, and has low 11 bits of the Offset
+        b0 = 0xF000 | (b_off >> 12 & 0x07FF)
+        b1 = 0xF800 | (b_off >> 1 & 0x7FF)
+        return struct.pack("<HH", b0, b1)
 
 
 def asm_jump_thumb2(entry):