diff --git a/lib/checkio.cpp b/lib/checkio.cpp
index 06f44d527..f2e01a75f 100644
--- a/lib/checkio.cpp
+++ b/lib/checkio.cpp
@@ -1774,7 +1774,7 @@ void CheckIO::invalidScanfArgTypeError_int(const Token* tok, nonneg int numForma
     errmsg << ".";
     reportError(tok, severity, "invalidScanfArgType_int", errmsg.str(), CWE686, false);
 }
-void CheckIO::invalidScanfArgTypeError_float(const Token* tok, unsigned int numFormat, const std::string& specifier, const ArgumentInfo* argInfo)
+void CheckIO::invalidScanfArgTypeError_float(const Token* tok, nonneg int numFormat, const std::string& specifier, const ArgumentInfo* argInfo)
 {
     const Severity::SeverityType severity = getSeverity(argInfo);
     if (!mSettings->isEnabled(severity))