diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 70db245c3..ff2c0746f 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -1744,8 +1744,8 @@ void CheckOther::checkMemsetInvalid2ndParam()
                 if (!secondParamTok)
                     continue;
 
-                // Second parameter is zero float literal, i.e. 0.0f
-                if (Token::Match(secondParamTok,"%num% ,") && secondParamTok->str().find_first_not_of("0.f") == std::string::npos)
+                // Second parameter is zero literal, i.e. 0.0f
+                if (Token::Match(secondParamTok, "%num% ,") && MathLib::isNullValue(secondParamTok->str()))
                     continue;
 
                 const Token *top = secondParamTok;
diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
index 518bed03d..bb0fb1147 100644
--- a/lib/mathlib.cpp
+++ b/lib/mathlib.cpp
@@ -600,15 +600,14 @@ bool MathLib::isLessEqual(const std::string &first, const std::string &second)
 
 bool MathLib::isNullValue(const std::string &str)
 {
-    return (str == "-0"        || str == "0"      || str == "+0"
-            || str == "-0.0"   || str == "0.0"    || str == "+0.0"
-            || str == "-0."    || str == "+0."
-            || str == "-0E-00" || str == "-0E+00" || str == "+0E+00" || str == "+0E-00"
-            || str == "-0e-00" || str == "-0e+00" || str == "+0e+00" || str == "+0e-00"
-            || str == "-0E-0");
+    for (size_t i = 0; i < str.size(); i++) {
+        if (std::isdigit(static_cast<unsigned char>(str[i])) && str[i] != '0') // May not contain digits other than 0
+            return false;
+    }
+    return !str.empty() && (std::isdigit(static_cast<unsigned char>(str[0])) || str[0] == '-' || str[0] == '+'); // Has to be a number
 }
 
 bool MathLib::isOctalDigit(char c)
 {
-    return (c == '0' || c == '1' || c == '2' || c == '3' || c == '4' || c == '5' || c == '6' || c == '7');
+    return (c >= '0' && c <= '7');
 }