Editing & Revision

How do I fix run-on sentences?

By the WriteLoom editorial teamUpdated 2026-06-04
Key facts
  • A run-on fuses independent clauses without correct punctuation.
  • Comma splices (joining clauses with only a comma) are a common form.
  • Fixes: split into sentences, add a conjunction, or use a semicolon.
  • Long is not the same as run-on; a long sentence can be correct.
  • Reading aloud and watching for breathlessness helps spot them.
Direct answer

Fix run-on sentences by finding where two independent clauses are joined incorrectly — fused with no punctuation, or spliced with just a comma — and repairing each: split into separate sentences, add a coordinating conjunction, or use a semicolon. Note that a long sentence is not automatically a run-on; the issue is grammatical joining, not length. Reading aloud and noticing where you run out of breath or lose the thread surfaces them quickly.

Chapter i·Why it matters

Run-ons and comma splices confuse readers and read as unpolished, undermining otherwise good prose. Because they often come from writing the way we think — clause piling onto clause — they slip in unnoticed. Learning to recognize the independent-clause boundary and apply the right fix cleans up clarity and rhythm. Distinguishing a true run-on from a correctly built long sentence also keeps you from chopping up prose that was fine.

Chapter ii·What to include

  • Identification of fused independent clauses.
  • A check for comma splices specifically.
  • Fixes: split, add a conjunction, or use a semicolon.
  • The distinction between long and run-on.
  • A read-aloud test for breathlessness.
  • Sentence variety preserved, not flattened.

Chapter iii·Example

A writer finds: "She opened the door, the room was empty." Two independent clauses joined by only a comma — a splice. She fixes it three possible ways and chooses a period for punch: "She opened the door. The room was empty." Across the chapter she repairs several splices without turning every sentence short and choppy.

In WriteLoom

WriteLoom's Edit studio supports a focused line pass, so run-ons and splices get caught without flattening your sentence variety.

See the Edit studio