diff --git a/lib/checkio.cpp b/lib/checkio.cpp
index 6a570e5e0..d3b789d74 100644
--- a/lib/checkio.cpp
+++ b/lib/checkio.cpp
@@ -941,8 +941,8 @@ void CheckIO::checkFormatString(const Token * const tok,
                                             if (argInfo.typeToken->str() != "int")
                                                 invalidScanfArgTypeError_int(tok, numFormat, specifier, &argInfo, true);
                                             else if (typesMatch(argInfo.typeToken->originalName(), "size_t") ||
-                                                     typesMatch(argInfo.typeToken->originalName(), "ssize_t") ||
-                                                     argInfo.typeToken->originalName() == "uintmax_t")
+                                                     typesMatch(argInfo.typeToken->originalName(), "ptrdiff_t") ||
+                                                     typesMatch(argInfo.typeToken->originalName(), "uintmax_t"))
                                                 invalidScanfArgTypeError_int(tok, numFormat, specifier, &argInfo, true);
                                             break;
                                         }