diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
index c540c73e8..0f778ee3a 100644
--- a/lib/mathlib.cpp
+++ b/lib/mathlib.cpp
@@ -131,6 +131,10 @@ bool MathLib::isFloat(const std::string &s)
         case LEADING_DECIMAL:
             if (std::isdigit(*it))
                 state=BASE_DIGITS2;
+            else if (*it=='e' || *it=='E')
+                state=E;
+            else
+                return false;
             break;
         case BASE_DIGITS1:
             if (*it=='e' || *it=='E')
diff --git a/test/testmathlib.cpp b/test/testmathlib.cpp
index ea4983155..f1b60db6e 100644
--- a/test/testmathlib.cpp
+++ b/test/testmathlib.cpp
@@ -368,6 +368,9 @@ private:
         ASSERT_EQUALS(false , MathLib::isFloat(" 0. "));
         ASSERT_EQUALS(false , MathLib::isFloat(" 0."));
 
+        ASSERT_EQUALS(false , MathLib::isFloat("0.."));
+        ASSERT_EQUALS(false , MathLib::isFloat("..0.."));
+        ASSERT_EQUALS(false , MathLib::isFloat("..0"));
         ASSERT_EQUALS(true , MathLib::isFloat("0.0"));
         ASSERT_EQUALS(true , MathLib::isFloat("-0."));
         ASSERT_EQUALS(true , MathLib::isFloat("+0."));