Balloon catheter and methods for making and using balloon catheters are disclosed. An example balloon catheter may include a proximal shaft. A midshaft may be attached to the proximal shaft. The midshaft may have an outer wall. A distal shaft may be attached to the midshaft. A balloon may be coupled to the distal shaft. An inflation lumen may be defined that extends from the proximal shaft, through the midshaft, and into the distal shaft. The inflation lumen may be in fluid communication with the balloon. A core wire may be disposed within the inflation lumen and may be attached to the midshaft.