diff --git a/lib/checktype.cpp b/lib/checktype.cpp
index c57aa913b..1060fb2fa 100644
--- a/lib/checktype.cpp
+++ b/lib/checktype.cpp
@@ -354,7 +354,7 @@ void CheckType::checkFloatToIntegerOverflow()
                         bits = _settings->long_long_bit;
                     else
                         continue;
-                    if (bits < 64 && it->floatValue > (1ULL << (bits - 1)))
+                    if (bits < 64 && it->floatValue >= (1ULL << bits))
                         floatToIntegerOverflowError(tok, *it);
                 }
             }
diff --git a/test/testtype.cpp b/test/testtype.cpp
index d4e20db28..8f59ac036 100644
--- a/test/testtype.cpp
+++ b/test/testtype.cpp
@@ -238,6 +238,16 @@ private:
               "  return (short)1E6;\n"
               "}\n");
         ASSERT_EQUALS("[test.cpp:2]: (error) Undefined behaviour: float () conversion overflow.\n", removeFloat(errout.str()));
+
+        check("void f(void) {\n"
+              "  return (unsigned char)256.0;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2]: (error) Undefined behaviour: float () conversion overflow.\n", removeFloat(errout.str()));
+
+        check("void f(void) {\n"
+              "  return (unsigned char)255.5;\n"
+              "}\n");
+        ASSERT_EQUALS("", removeFloat(errout.str()));
     }
 };