diff --git a/lex.ll b/lex.ll
index 3d88a23a..ca318dbb 100644
--- a/lex.ll
+++ b/lex.ll
@@ -345,7 +345,9 @@ 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]?)
-FORTRAN_DOUBLE_NUMBER (([0-9]+\.[0-9]*[dD])|([0-9]+\.[0-9]*[dD][-+]?[0-9])|([0-9]+[dD][-+]?[0-9]))
+FORTRAN_DOUBLE_NUMBER (([0-9]+\.[0-9]*[dD])|([0-9]+\.[0-9]*[dD][-+]?[0-9]+)|([0-9]+[dD][-+]?[0-9]+))
+
+
 
 IDENT [a-zA-Z_][a-zA-Z_0-9]*
 ZO_SWIZZLE ([01]+[w-z]+)+|([01]+[rgba]+)+|([01]+[uv]+)+
@@ -440,6 +442,16 @@ L?\"(\\.|[^\\"])*\" { lStringConst(&yylval, &yylloc); return TOKEN_STRING_LITERA
     return lParseInteger(true);
 }
 
+{FORTRAN_DOUBLE_NUMBER} {
+    RT;
+    {
+      int i = 0;
+      while (yytext[i] != 'd') i++;
+      yytext[i] = 'E';
+    }
+    yylval.doubleVal = atof(yytext);
+    return TOKEN_DOUBLE_CONSTANT;
+}
 
 
 {FLOAT_NUMBER} {
@@ -454,18 +466,6 @@ L?\"(\\.|[^\\"])*\" { lStringConst(&yylval, &yylloc); return TOKEN_STRING_LITERA
     return TOKEN_FLOAT_CONSTANT;
 }
 
-{FORTRAN_DOUBLE_NUMBER} {
-    RT;
-    {
-      int i = 0;
-      while (yytext[i] != 'd') i++;
-      if ((yytext[i+1] >= '0' && yytext[i+1] <= '9') 
-          || yytext[i+1] == '+' || yytext[i+1] == '-')
-        yytext[i] = 'E';
-    }
-    yylval.doubleVal = atof(yytext);
-    return TOKEN_DOUBLE_CONSTANT;
-}
 
 
 "++" { RT; return TOKEN_INC_OP; }
diff --git a/stdlib.ispc b/stdlib.ispc
index 0d5c4efd..9b02d0ba 100644
--- a/stdlib.ispc
+++ b/stdlib.ispc
@@ -2564,7 +2564,7 @@ static inline float acos(float v) {
 
 __declspec(safe)
 static inline double acos(const double v) {
-    return 1.57079637050628662109375 - asin(v);
+    return 1.57079637050628662109375d0 - asin(v);
 }
 
 
@@ -2575,7 +2575,7 @@ static inline uniform float acos(uniform float v) {
 
 __declspec(safe)
 static inline uniform double acos(const uniform double v) {
-    return 1.57079637050628662109375 - asin(v);
+    return 1.57079637050628662109375d0 - asin(v);
 }