diff --git a/lex.ll b/lex.ll
index 8baa627a..c2990ccc 100644
--- a/lex.ll
+++ b/lex.ll
@@ -76,7 +76,7 @@ static int allTokens[] = {
   TOKEN_TASK, TOKEN_TRUE, TOKEN_TYPEDEF, TOKEN_UNIFORM, TOKEN_UNMASKED,
   TOKEN_UNSIGNED, TOKEN_VARYING, TOKEN_VOID, TOKEN_WHILE,
   TOKEN_STRING_C_LITERAL, TOKEN_DOTDOTDOT,
-  TOKEN_FLOAT_CONSTANT,
+  TOKEN_FLOAT_CONSTANT, TOKEN_DOUBLE_CONSTANT,
   TOKEN_INT8_CONSTANT, TOKEN_UINT8_CONSTANT,
   TOKEN_INT16_CONSTANT, TOKEN_UINT16_CONSTANT,
   TOKEN_INT32_CONSTANT, TOKEN_UINT32_CONSTANT,
@@ -152,6 +152,7 @@ void ParserInit() {
     tokenToName[TOKEN_STRING_C_LITERAL] = "\"C\"";
     tokenToName[TOKEN_DOTDOTDOT] = "...";
     tokenToName[TOKEN_FLOAT_CONSTANT] = "TOKEN_FLOAT_CONSTANT";
+    tokenToName[TOKEN_DOUBLE_CONSTANT] = "TOKEN_DOUBLE_CONSTANT";
     tokenToName[TOKEN_INT8_CONSTANT] = "TOKEN_INT8_CONSTANT";
     tokenToName[TOKEN_UINT8_CONSTANT] = "TOKEN_UINT8_CONSTANT";
     tokenToName[TOKEN_INT16_CONSTANT] = "TOKEN_INT16_CONSTANT";
@@ -266,6 +267,7 @@ void ParserInit() {
     tokenNameRemap["TOKEN_STRING_C_LITERAL"] = "\"C\"";
     tokenNameRemap["TOKEN_DOTDOTDOT"] = "\'...\'";
     tokenNameRemap["TOKEN_FLOAT_CONSTANT"] = "float constant";
+    tokenNameRemap["TOKEN_DOUBLE_CONSTANT"] = "double constant";
     tokenNameRemap["TOKEN_INT8_CONSTANT"] = "int8 constant";
     tokenNameRemap["TOKEN_UINT8_CONSTANT"] = "unsigned int8 constant";
     tokenNameRemap["TOKEN_INT16_CONSTANT"] = "int16 constant";
@@ -343,6 +345,8 @@ INT_NUMBER (([0-9]+)|(0x[0-9a-fA-F]+)|(0b[01]+))[uUlL]*[kMG]?[uUlL]*
 INT_NUMBER_DOTDOTDOT (([0-9]+)|(0x[0-9a-fA-F]+)|(0b[01]+))[uUlL]*[kMG]?[uUlL]*\.\.\.
 FLOAT_NUMBER (([0-9]+|(([0-9]+\.[0-9]*[fF]?)|(\.[0-9]+)))([eE][-+]?[0-9]+)?[fF]?)
 HEX_FLOAT_NUMBER (0x[01](\.[0-9a-fA-F]*)?p[-+]?[0-9]+[fF]?)
+DOUBLE_NUMBER (([0-9]+|(([0-9]+\.[0-9]*[dD]?)|(\.[0-9]+)))([dD][-+]?[0-9]+)?[dD]?)
+HEX_DOUBLE_NUMBER (0x[01](\.[0-9a-fA-F]*)?p[-+]?[0-9]+[dD]?)
 
 IDENT [a-zA-Z_][a-zA-Z_0-9]*
 ZO_SWIZZLE ([01]+[w-z]+)+|([01]+[rgba]+)+|([01]+[uv]+)+
@@ -438,6 +442,7 @@ L?\"(\\.|[^\\"])*\" { lStringConst(&yylval, &yylloc); return TOKEN_STRING_LITERA
 }
 
 
+
 {FLOAT_NUMBER} {
     RT;
     yylval.floatVal = (float)atof(yytext);
@@ -450,6 +455,19 @@ L?\"(\\.|[^\\"])*\" { lStringConst(&yylval, &yylloc); return TOKEN_STRING_LITERA
     return TOKEN_FLOAT_CONSTANT;
 }
 
+{DOUBLE_NUMBER} {
+    RT;
+    yylval.doubleVal = atof(yytext);
+    return TOKEN_DOUBLE_CONSTANT;
+}
+
+{HEX_DOUBLE_NUMBER} {
+    RT;
+    yylval.doubleVal = lParseHexFloat(yytext);
+    return TOKEN_DOUBLE_CONSTANT;
+}
+
+
 "++" { RT; return TOKEN_INC_OP; }
 "--" { RT; return TOKEN_DEC_OP; }
 "<<" { RT; return TOKEN_LEFT_OP; }
diff --git a/parse.yy b/parse.yy
index 9a2b4fc3..933a3455 100644
--- a/parse.yy
+++ b/parse.yy
@@ -149,7 +149,8 @@ struct ForeachDimension {
 
 %union {
     uint64_t intVal;
-    float floatVal;
+    float  floatVal;
+    double doubleVal;
     std::string *stringVal;
     const char *constCharPtr;
 
@@ -185,7 +186,7 @@ struct ForeachDimension {
 %token TOKEN_INT64_CONSTANT TOKEN_UINT64_CONSTANT
 %token TOKEN_INT32DOTDOTDOT_CONSTANT TOKEN_UINT32DOTDOTDOT_CONSTANT
 %token TOKEN_INT64DOTDOTDOT_CONSTANT TOKEN_UINT64DOTDOTDOT_CONSTANT
-%token TOKEN_FLOAT_CONSTANT TOKEN_STRING_C_LITERAL
+%token TOKEN_FLOAT_CONSTANT TOKEN_DOUBLE_CONSTANT TOKEN_STRING_C_LITERAL
 %token TOKEN_IDENTIFIER TOKEN_STRING_LITERAL TOKEN_TYPE_NAME TOKEN_NULL
 %token TOKEN_PTR_OP TOKEN_INC_OP TOKEN_DEC_OP TOKEN_LEFT_OP TOKEN_RIGHT_OP
 %token TOKEN_LE_OP TOKEN_GE_OP TOKEN_EQ_OP TOKEN_NE_OP
@@ -327,7 +328,11 @@ primary_expression
     }
     | TOKEN_FLOAT_CONSTANT {
         $$ = new ConstExpr(AtomicType::UniformFloat->GetAsConstType(),
-                           (float)yylval.floatVal, @1);
+                           yylval.floatVal, @1);
+    }
+    | TOKEN_DOUBLE_CONSTANT {
+        $$ = new ConstExpr(AtomicType::UniformDouble->GetAsConstType(),
+                           yylval.doubleVal, @1);
     }
     | TOKEN_TRUE {
         $$ = new ConstExpr(AtomicType::UniformBool->GetAsConstType(), true, @1);
diff --git a/stdlib.ispc b/stdlib.ispc
index 6d7ee051..0d5c4efd 100644
--- a/stdlib.ispc
+++ b/stdlib.ispc
@@ -1559,6 +1559,18 @@ static inline uniform float clamp(uniform float v, uniform float low, uniform fl
     return min(max(v, low), high);
 }
 
+// double
+
+__declspec(safe,cost2)
+static inline double clamp(double v, double low, double high) {
+    return min(max(v, low), high);
+}
+
+__declspec(safe,cost2)
+static inline uniform double clamp(uniform double v, uniform double low, uniform double high) {
+    return min(max(v, low), high);
+}
+
 // int8
 
 __declspec(safe,cost2)