diff --git a/include/internal/catch_matchers_floating.cpp b/include/internal/catch_matchers_floating.cpp
index bcca0725..6fefe987 100644
--- a/include/internal/catch_matchers_floating.cpp
+++ b/include/internal/catch_matchers_floating.cpp
@@ -55,7 +55,8 @@ namespace {
             return lhs == rhs;
         }
 
-        auto ulpDiff = std::abs(lc - rc);
+        // static cast as a workaround for IBM XLC
+        auto ulpDiff = std::abs(static_cast<FP>(lc - rc));
         return static_cast<uint64_t>(ulpDiff) <= maxUlpDiff;
     }
 
@@ -234,4 +235,3 @@ Floating::WithinRelMatcher WithinRel(float target) {
 
 } // namespace Matchers
 } // namespace Catch
-