St. Louis Blues forward Jaden Schwartz, who's from Wilcox, Sask., is changing from his No. 9 to the 17 that Mandi Schwartz wore when she played three years with Yale University's women's hockey team.
She lost her 2½-year struggle with acute myeloid leukemia in 2011 at age 23.
Jaden, who took No. 9 when he made his NHL debut in 2012, had often spoken of his sister being his inspiration.
After the Blues player wearing No. 17, Vladimir Sobotka, moved on from the team last week, Schwartz asked if he could have it.
When the answer was yes, Schwartz, 22, announced it on his Twitter account last week.
"Sorry to the fans with #9 apparel but when I'm back in uniform I'll be looking a little different this year," he said.
His mother, Carol Schwartz, says the number change was a surprise.
"I think he was a little bit hesitant. He didn't know what they would say about changing his number because that's not something that's done a whole bunch in the league," she said. "But in his circumstance, it was approved for him, so that was pretty special."
Carol Schwartz said the number change means a lot to her son.
"He's always stated that what he does he does for her, because she loved hockey so much," she said. "I mean, he loves it too, but I think he just pushes himself a little bit more and uses her as his role model."
Mandi's search for a bone marrow match led thousands of people across Saskatchewan and North America to sign up as donors.
An annual bone marrow drive continues to be held in her honour.