diff --git a/src/builtin.c b/src/builtin.c
index 30cd380b9501..6ec705e676b7 100644
--- a/src/builtin.c
+++ b/src/builtin.c
@@ -44,7 +44,7 @@ enum BUILTIN FuncDeclaration::isBuiltin()
     static const char FeZe [] = "FNaNbNfeZe";      // @safe pure nothrow real function(real)
     static const char FeZe2[] = "FNaNbNeeZe";      // @trusted pure nothrow real function(real)
 
-    //printf("FuncDeclaration::isBuiltin() %s\n", toChars());
+    //printf("FuncDeclaration::isBuiltin() %s, %d\n", toChars(), builtin);
     if (builtin == BUILTINunknown)
     {
         builtin = BUILTINnot;
@@ -52,7 +52,7 @@ enum BUILTIN FuncDeclaration::isBuiltin()
         {
             // If it's in the std.math package
             if (parent->ident == Id::math &&
-                parent->parent && parent->parent->ident == Id::std &&
+                parent->parent && (parent->parent->ident == Id::std || parent->parent->ident == Id::core) &&
                 !parent->parent->parent)
             {
                 //printf("deco = %s\n", type->deco);
diff --git a/src/idgen.c b/src/idgen.c
index c45668c1e366..6f90d8aaf778 100644
--- a/src/idgen.c
+++ b/src/idgen.c
@@ -284,6 +284,7 @@ Msgtable msgtable[] =
 
     // Builtin functions
     { "std" },
+    { "core" },
     { "math" },
     { "sin" },
     { "cos" },
diff --git a/src/toir.c b/src/toir.c
index 200cb307ead0..9ccaf62e1d2e 100644
--- a/src/toir.c
+++ b/src/toir.c
@@ -488,6 +488,18 @@ int intrinsic_op(char *name)
 #ifdef DMDV2
     static const char *core_namearray[] =
     {
+        "4math3cosFNaNbNfeZe",
+        "4math3sinFNaNbNfeZe",
+        "4math4fabsFNaNbNfeZe",
+        "4math4rintFNaNbNfeZe",
+        "4math4sqrtFNaNbNfdZd",
+        "4math4sqrtFNaNbNfeZe",
+        "4math4sqrtFNaNbNffZf",
+        "4math4yl2xFNaNbNfeeZe",
+        "4math5ldexpFNaNbNfeiZe",
+        "4math6rndtolFNaNbNfeZl",
+        "4math6yl2xp1FNaNbNfeeZe",
+
         "5bitop2btFNaNbxPkkZi",
         "5bitop3bsfFNaNbkZi",
         "5bitop3bsrFNaNbkZi",
@@ -504,6 +516,18 @@ int intrinsic_op(char *name)
     };
     static const char *core_namearray64[] =
     {
+        "4math3cosFNaNbNfeZe",
+        "4math3sinFNaNbNfeZe",
+        "4math4fabsFNaNbNfeZe",
+        "4math4rintFNaNbNfeZe",
+        "4math4sqrtFNaNbNfdZd",
+        "4math4sqrtFNaNbNfeZe",
+        "4math4sqrtFNaNbNffZf",
+        "4math4yl2xFNaNbNfeeZe",
+        "4math5ldexpFNaNbNfeiZe",
+        "4math6rndtolFNaNbNfeZl",
+        "4math6yl2xp1FNaNbNfeeZe",
+
         "5bitop2btFNaNbxPmmZi",
         "5bitop3bsfFNaNbmZi",
         "5bitop3bsrFNaNbmZi",
@@ -520,6 +544,18 @@ int intrinsic_op(char *name)
     };
     static unsigned char core_ioptab[] =
     {
+        OPcos,
+        OPsin,
+        OPabs,
+        OPrint,
+        OPsqrt,
+        OPsqrt,
+        OPsqrt,
+        OPyl2x,
+        OPscale,
+        OPrndtol,
+        OPyl2xp1,
+
         OPbt,
         OPbsf,
         OPbsr,
@@ -589,7 +625,7 @@ int intrinsic_op(char *name)
     }
 #ifdef DMDV2
     if (length > 12 &&
-        name[8] == 'b' &&
+        (name[8] == 'm' || name[8] == 'b') &&
         !memcmp(name, "_D4core", 7))
     {
         int i = binary(name + 7, I64 ? core_namearray64 : core_namearray, sizeof(core_namearray) / sizeof(char *));