diff --git a/src/lib/isFloat.js b/src/lib/isFloat.js
index 84bdc782c..d877ae15b 100644
--- a/src/lib/isFloat.js
+++ b/src/lib/isFloat.js
@@ -10,6 +10,9 @@ export default function isFloat(str, options) {
     return false;
   }
   const value = parseFloat(str.replace(',', '.'));
+  if (Number.isNaN(value)) {
+    return false;
+  }
   return float.test(str) &&
     (!options.hasOwnProperty('min') || isNullOrUndefined(options.min) || value >= options.min) &&
     (!options.hasOwnProperty('max') || isNullOrUndefined(options.max) || value <= options.max) &&
diff --git a/test/validators.test.js b/test/validators.test.js
index cdde41a07..873f9d1db 100644
--- a/test/validators.test.js
+++ b/test/validators.test.js
@@ -4657,6 +4657,11 @@ describe('Validators', () => {
         'foo',
         '20.foo',
         '2020-01-06T14:31:00.135Z',
+        'e5',
+        'E5',
+        '.e3',
+        'e-3',
+        '+e5',
       ],
     });