diff --git a/Docs/src/compiler.but b/Docs/src/compiler.but
index dd69d215..8903efab 100644
--- a/Docs/src/compiler.but
+++ b/Docs/src/compiler.but
@@ -2,7 +2,9 @@
 
 \S0{compcommands} Compiler Utility Commands
 
-These commands are similar to the C preprocessor in terms of purpose and functionality. They allow file inclusion, conditional compilation, executable header packing, and processes execution during the build process. Note: none of these commands allow use of variables.
+These commands are similar to the C preprocessor in terms of purpose and functionality. They allow file inclusion, conditional compilation, executable header packing, and processes execution during the build process. Note: None of these commands allow the use of variables.
+
+Number literals support the \c{0b}, \c{0o}, \c{0n} and \c{0x} radix prefixes (base 2, 8, 10 and 16 respectively). Note: The deprecated plain \c{0} octal prefix is also supported in some places but its usage is discouraged.
 
 \S1{include} !include
 
diff --git a/Docs/src/history.but b/Docs/src/history.but
index 2f996a29..9745fc8e 100644
--- a/Docs/src/history.but
+++ b/Docs/src/history.but
@@ -20,6 +20,12 @@ Released on ? ?th, 201?
 
 \b !system and !execute now provide a empty StdIn pipe to work around bugs in some Windows utilities
 
+\b Added support for 0o octal radix prefix on number literals in the preprocessor
+
+\b The single parameter version of !if now also supports floats
+
+\b Preprocessor now warns when invalid floating point numbers are used in math operations
+
 \b MakeNSISW now uses WinInet when checking for updates
 
 \S2{} Translations
diff --git a/Source/lineparse.cpp b/Source/lineparse.cpp
index 3bda35cf..e9527dbf 100644
--- a/Source/lineparse.cpp
+++ b/Source/lineparse.cpp
@@ -90,8 +90,10 @@ double LineParser::gettoken_float(int token, int *success/*=0*/) const
     TCHAR *t=m_tokens[token];
     if (_T('-') == *t || _T('+') == *t) ++t;
     *success=*t?1:0;
+    unsigned int dotcount = 0;
     while (*t)
     {
+      if (_T('.') == *t && ++dotcount > 1) *success=0;
       if ((*t < _T('0') || *t > _T('9'))&&*t != _T('.')) *success=0;
       t++;
     }
@@ -116,9 +118,10 @@ int LineParser::gettoken_int(int token, int *success/*=0*/) const
     ++p, ++neg;
   if (_T('0') == p[0])
   {
-    // Special support for 0n and 0y MASM style and 0b Python style radix prefix:
+    // Special support for 0n, 0y and 0t MASM style and 0b and 0o Python style radix prefix:
     if (_T('n') == (p[1]|32)) parse=&p[2], base=10;
     if (_T('b') == (p[1]|32) || _T('y') == (p[1]|32)) parse=&p[2], base=2;
+    if (_T('o') == (p[1]|32) || _T('t') == (p[1]|32)) parse=&p[2], base=8;
   }
   if (neg)
   {
@@ -143,6 +146,7 @@ double LineParser::gettoken_number(int token, int *success/*=0*/) const
     if (_T('x') == (str[1]|32)) ++forceint;
     if (_T('n') == (str[1]|32)) ++forceint;
     if (_T('b') == (str[1]|32) || _T('y') == (str[1]|32)) ++forceint;
+    if (_T('o') == (str[1]|32) || _T('t') == (str[1]|32)) ++forceint;
   }
   return forceint ? gettoken_int(token,success) : gettoken_float(token,success);
 }
diff --git a/Source/script.cpp b/Source/script.cpp
index 3a32eaec..0e311696 100644
--- a/Source/script.cpp
+++ b/Source/script.cpp
@@ -517,7 +517,7 @@ parse_again:
         logicneg++, line.eattoken();
 
       if (line.getnumtokens() == 2)
-        istrue = line.gettoken_int(1);
+        istrue = line.gettoken_number(1) || line.gettoken_int(1);
 
       else if (line.getnumtokens() == 3) {
         if (!_tcsicmp(line.gettoken_str(1),_T("/fileexists"))) {