diff --git a/Ghidra/Features/Base/src/main/javacc/ghidra/app/util/cparser/C/C.jj b/Ghidra/Features/Base/src/main/javacc/ghidra/app/util/cparser/C/C.jj
index 49d6bd44d4..f295183396 100644
--- a/Ghidra/Features/Base/src/main/javacc/ghidra/app/util/cparser/C/C.jj
+++ b/Ghidra/Features/Base/src/main/javacc/ghidra/app/util/cparser/C/C.jj
@@ -1079,11 +1079,11 @@ SKIP :
 TOKEN :
 {
     <INTEGER_LITERAL : 
-        <DECIMAL_LITERAL> (  "ull" | "ULL" | "ul" | "UL" | "ll" | "LL" | "l" | "L" | "U" | "u")? ("i")? ( ["0"-"9"] )*
+        <DECIMAL_LITERAL> ("u"|"U")? ("ll"|"LL"|"l"|"L")? (("i"|"I") ("8"|"16"|"32"|"64"|"128"))?
         |
-        <HEX_LITERAL> ( "ull" | "ULL" | "ul" | "UL" | "ll" | "LL" | "l" | "L" | "U" | "u")? ("i")? ( ["0"-"9"] )*
+        <HEX_LITERAL> ("u"|"U")? ("ll"|"LL"|"l"|"L")? (("i"|"I") ("8"|"16"|"32"|"64"|"128"))?
         |
-        <OCTAL_LITERAL> ( "ull" | "ULL" | "ul" | "UL" | "ll" | "LL" | "l" | "L" | "U" | "u")? ("i")? ( ["0"-"9"] )*
+        <OCTAL_LITERAL> ("u"|"U")? ("ll"|"LL"|"l"|"L")? (("i"|"I") ("8"|"16"|"32"|"64"|"128"))?
     >
     |
     <#DECIMAL_LITERAL : [ "1"-"9" ] ( [ "0"-"9" ] )*> 
@@ -3079,39 +3079,46 @@ Object Constant() : {
     (
         t = <INTEGER_LITERAL>
         {
-            String sval = t.image;
-            if (sval.endsWith("i8") || sval.endsWith("I8")) {
+            String sval = t.image.toLowerCase();
+            if (sval.endsWith("i8")) {
                 sval = sval.substring(0,sval.length()-2);
             }
-            else if (sval.endsWith("i16") || sval.endsWith("I16")) {
+            else if (sval.endsWith("i16")) {
                 sval = sval.substring(0,sval.length()-3);
             }
-            else if (sval.endsWith("i32") || sval.endsWith("I32")) {
+            else if (sval.endsWith("i32")) {
                 sval = sval.substring(0,sval.length()-3);
             }
-            else if (sval.endsWith("i64") || sval.endsWith("I64")) {
+            else if (sval.endsWith("i64")) {
                 sval = sval.substring(0,sval.length()-3);
             }
+            else if (sval.endsWith("i128")) {
+                sval = sval.substring(0,sval.length()-4);
+            }
             
-            if (sval.endsWith("ull") || sval.endsWith("ULL")) {
+            if (sval.endsWith("ull")) {
                 sval = sval.substring(0,sval.length()-3);
             }
-            else if (sval.endsWith("ll") || sval.endsWith("LL")) {
+            else if (sval.endsWith("ll")) {
                 sval = sval.substring(0,sval.length()-2);
             }
-            else if (sval.endsWith("ul") || sval.endsWith("UL")) {
+            else if (sval.endsWith("ul")) {
                 sval = sval.substring(0,sval.length()-2);
             }
-            else if (sval.endsWith("l") || sval.endsWith("L")) {
+            else if (sval.endsWith("l")) {
                 sval = sval.substring(0,sval.length()-1);
             }
-            else if (sval.endsWith("u") || sval.endsWith("U")) {
+            else if (sval.endsWith("u")) {
                 sval = sval.substring(0,sval.length()-1);
             }
-            if (sval.startsWith("0x") || sval.startsWith("0X")) {
+            if (sval.startsWith("0x")) {
                 BigInteger bigConst = new BigInteger(sval.substring(2), 16);           
                 obj = Long.valueOf(bigConst.longValue());
             }
+            else if (sval.startsWith("0")) {
+                BigInteger bigConst = new BigInteger(sval, 8);           
+                obj = Long.valueOf(bigConst.longValue());
+            }
             else {
                 BigInteger bigConst = new BigInteger(sval);           
                 obj = Long.valueOf(bigConst.longValue());
diff --git a/Ghidra/Features/Base/src/test/resources/ghidra/app/util/cparser/CParserTest.h b/Ghidra/Features/Base/src/test/resources/ghidra/app/util/cparser/CParserTest.h
index 0b536ee0e7..114d618b98 100644
--- a/Ghidra/Features/Base/src/test/resources/ghidra/app/util/cparser/CParserTest.h
+++ b/Ghidra/Features/Base/src/test/resources/ghidra/app/util/cparser/CParserTest.h
@@ -1189,8 +1189,37 @@ void multilineStrings(void)
     char b[] = "This is a "
                "multiline string.";
 }
- 
 
+/**
+ ** Constants
+ **/
+ /* Decimal */
+ int                 d_int    = 123;
+ unsigned            d_uint   = 4000000123u;
+ long                d_long   = 1000000123l;
+ unsigned long       d_ulong  = 7000000001ul;
+ long long           d_llong  = 6000000002LL;
+ unsigned long long  d_ullong = 50000000003ull;
+ __int64             d_i64    = 500000000004I64;
+ unsigned __int64    d_ui64   = 5000000000005ui64;
+ /* Octal */
+ int                 o_int    = 01234;
+ unsigned            o_uint   = 04000000012u;
+ long                o_long   = 02000000024l;
+ unsigned long       o_ulong  = 01000000001UL;
+ long long           o_llong  = 01100000000002ll;
+ unsigned long long  o_ullong = 01110000000000003Ull;
+ __int64             o_i64    = 0111100000000000004i64;
+ unsigned __int64    o_ui64   = 0222200000000000005uI64;
+ /* Hexadecimal  */
+ int                 h_int    = 0x123b;
+ unsigned            h_uint   = 0XB0000012u;
+ long                h_long   = 0x20000034l;
+ unsigned long       h_ulong  = 0XA0000056uL;
+ long long           h_llong  = 0x8b00000000000ll;
+ unsigned long long  h_ullong = 0xAC4000000000012uLL;
+ __int64             h_i64    = 0x6d2200000000023I64;
+ unsigned __int64    h_ui64   = 0x7e4400000000034Ui64;
 
 /**
  ** #line in structure/function body