diff --git a/src/core/arm7tdmi/thumb/display.rs b/src/core/arm7tdmi/thumb/display.rs
index 3d605ea..08ee6d2 100644
--- a/src/core/arm7tdmi/thumb/display.rs
+++ b/src/core/arm7tdmi/thumb/display.rs
@@ -216,6 +216,7 @@ impl ThumbInstruction {
                 if has_first {
                     write!(f, ", {}", reg_string(i))?;
                 } else {
+                    has_first = true;
                     write!(f, "{}", reg_string(i))?;
                 }
             }