diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
index a6fb9608c..a8b047a0a 100644
--- a/lib/mathlib.cpp
+++ b/lib/mathlib.cpp
@@ -126,10 +126,88 @@ bool MathLib::isPositive(const std::string &s)
     return !MathLib::isNegative(s);
 }
 
-bool MathLib::isOct(const std::string& str)
+/*! \brief Does the string represent an octal number?
+ * In case leading or trailing white space is provided, the function
+ * returns false.
+ * Additional information can be found here:
+ * http://gcc.gnu.org/onlinedocs/gcc/Binary-constants.html
+ *
+ * \param[in] s The string to check. In case the string is empty, the function returns false.
+ * \return Return true in case a octal number is provided and false otherwise.
+ **/
+bool MathLib::isOct(const std::string& s)
 {
-    const bool sign = str[0]=='-' || str[0]=='+';
-    return (str[sign?1:0] == '0' && (str.size() == 1 || isOctalDigit(str[sign?2:1])) && !isFloat(str));
+    enum {START, PLUSMINUS, OCTAL_PREFIX, DIGITS, UNSIGNED_SUFFIX, SUFFIX_U, SUFFIX_UL, SUFFIX_ULL, SUFFIX_L, SUFFIX_LU, SUFFIX_LL, SUFFIX_LLU} state = START;
+    for (std::string::const_iterator it = s.begin(); it != s.end(); ++it) {
+        switch (state) {
+        case START:
+            if (*it == '+' || *it == '-')
+                state = PLUSMINUS;
+            else if (*it == '0')
+                state = OCTAL_PREFIX;
+            else
+                return false;
+            break;
+        case PLUSMINUS:
+            if (*it == '0')
+                state = OCTAL_PREFIX;
+            else
+                return false;
+            break;
+
+        case OCTAL_PREFIX:
+            if (isOctalDigit(*it))
+                state = DIGITS;
+            else
+                return false;
+            break;
+        case DIGITS:
+            if (isOctalDigit(*it))
+                state = DIGITS;
+            else if (*it == 'u' || *it == 'U')
+                state = SUFFIX_U;
+            else if (*it == 'l' || *it == 'L')
+                state = SUFFIX_L;
+            else
+                return false;
+            break;
+        case SUFFIX_U:
+            if (*it == 'l' || *it == 'L')
+                state = SUFFIX_UL; // UL
+            else
+                return false;
+            break;
+        case SUFFIX_UL:
+            if (*it == 'l' || *it == 'L')
+                state = SUFFIX_ULL; // ULL
+            else
+                return false;
+            break;
+        case SUFFIX_L:
+            if (*it == 'u' || *it == 'U')
+                state = SUFFIX_LU; // LU
+            else if (*it == 'l' || *it == 'L')
+                state = SUFFIX_LL; // LL
+            else
+                return false;
+            break;
+        case SUFFIX_LU:
+            return false;
+            break;
+        case SUFFIX_LL:
+            if (*it == 'u' || *it == 'U')
+                state = SUFFIX_LLU; // LLU
+            else
+                return false;
+            break;
+        default:
+            return false;
+        }
+    }
+    return (state == DIGITS)
+           || (state == SUFFIX_U)  || (state == SUFFIX_L)
+           || (state == SUFFIX_UL) || (state == SUFFIX_LU)   || (state == SUFFIX_LL)
+           || (state == SUFFIX_ULL) || (state == SUFFIX_LLU);
 }
 
 bool MathLib::isHex(const std::string& str)
diff --git a/test/testmathlib.cpp b/test/testmathlib.cpp
index 0ed5a38c1..9439c9dd6 100644
--- a/test/testmathlib.cpp
+++ b/test/testmathlib.cpp
@@ -34,6 +34,7 @@ private:
         TEST_CASE(convert);
         TEST_CASE(isint);
         TEST_CASE(isbin);
+        TEST_CASE(isoct);
         TEST_CASE(isnegative);
         TEST_CASE(ispositive);
         TEST_CASE(isfloat);
@@ -367,6 +368,67 @@ private:
         ASSERT_EQUALS(false, MathLib::isNegative("+1.0E-2"));
     }
 
+    void isoct() {
+        // octal number format: [+|-]0[0-7][suffix]
+        // positive testing
+        ASSERT_EQUALS(true, MathLib::isOct("010"));
+        ASSERT_EQUALS(true, MathLib::isOct("+010"));
+        ASSERT_EQUALS(true, MathLib::isOct("-010"));
+        ASSERT_EQUALS(true, MathLib::isOct("0175"));
+        ASSERT_EQUALS(true, MathLib::isOct("+0175"));
+        ASSERT_EQUALS(true, MathLib::isOct("-0175"));
+        ASSERT_EQUALS(true, MathLib::isOct("00"));
+        ASSERT_EQUALS(true, MathLib::isOct("02"));
+        ASSERT_EQUALS(true, MathLib::isOct("+042"));
+        ASSERT_EQUALS(true, MathLib::isOct("-042"));
+        ASSERT_EQUALS(true, MathLib::isOct("+042U"));
+        ASSERT_EQUALS(true, MathLib::isOct("-042U"));
+        ASSERT_EQUALS(true, MathLib::isOct("+042L"));
+        ASSERT_EQUALS(true, MathLib::isOct("-042L"));
+        ASSERT_EQUALS(true, MathLib::isOct("+042LU"));
+        ASSERT_EQUALS(true, MathLib::isOct("-042LU"));
+        ASSERT_EQUALS(true, MathLib::isOct("+042UL"));
+        ASSERT_EQUALS(true, MathLib::isOct("-042UL"));
+        ASSERT_EQUALS(true, MathLib::isOct("+042ULL"));
+        ASSERT_EQUALS(true, MathLib::isOct("-042ULL"));
+        ASSERT_EQUALS(true, MathLib::isOct("+042LLU"));
+        ASSERT_EQUALS(true, MathLib::isOct("-042LLU"));
+
+        // test empty string
+        ASSERT_EQUALS(false, MathLib::isOct(""));
+
+        // negative testing
+        ASSERT_EQUALS(false, MathLib::isOct("0"));
+        ASSERT_EQUALS(false, MathLib::isOct("-0x175"));
+        ASSERT_EQUALS(false, MathLib::isOct("-0_garbage_"));
+        ASSERT_EQUALS(false, MathLib::isOct("  "));
+        ASSERT_EQUALS(false, MathLib::isOct(" "));
+        ASSERT_EQUALS(false, MathLib::isOct("02."));
+        ASSERT_EQUALS(false, MathLib::isOct("02E2"));
+        ASSERT_EQUALS(false, MathLib::isOct("+042x"));
+        ASSERT_EQUALS(false, MathLib::isOct("-042x"));
+        ASSERT_EQUALS(false, MathLib::isOct("+042Ux"));
+        ASSERT_EQUALS(false, MathLib::isOct("-042Ux"));
+        ASSERT_EQUALS(false, MathLib::isOct("+042Lx"));
+        ASSERT_EQUALS(false, MathLib::isOct("-042Lx"));
+        ASSERT_EQUALS(false, MathLib::isOct("+042ULx"));
+        ASSERT_EQUALS(false, MathLib::isOct("-042ULx"));
+        ASSERT_EQUALS(false, MathLib::isOct("+042LLx"));
+        ASSERT_EQUALS(false, MathLib::isOct("-042LLx"));
+        ASSERT_EQUALS(false, MathLib::isOct("+042ULLx"));
+        ASSERT_EQUALS(false, MathLib::isOct("-042ULLx"));
+        ASSERT_EQUALS(false, MathLib::isOct("+042LLUx"));
+        ASSERT_EQUALS(false, MathLib::isOct("-042LLUx"));
+        ASSERT_EQUALS(false, MathLib::isOct("+042LUL"));
+        ASSERT_EQUALS(false, MathLib::isOct("-042LUL"));
+        // white space in front
+        ASSERT_EQUALS(false, MathLib::isOct(" -042ULL"));
+        // trailing white space
+        ASSERT_EQUALS(false, MathLib::isOct("-042ULL  "));
+        // front and trailing white space
+        ASSERT_EQUALS(false, MathLib::isOct("  -042ULL  "));
+    }
+
     void ispositive() const {
         ASSERT_EQUALS(false, MathLib::isPositive("-1"));
         ASSERT_EQUALS(false, MathLib::isPositive("-1."));