diff --git a/std/net/curl.d b/std/net/curl.d
index 348ab107d..15389f7c5 100644
--- a/std/net/curl.d
+++ b/std/net/curl.d
@@ -476,7 +476,7 @@ if (isCurlConn!Conn)
         import std.stdio : File;
         auto f = File(loadFromPath, "rb");
         conn.onSend = buf => f.rawRead(buf).length;
-        auto sz = f.size;
+        immutable sz = f.size;
         if (sz != ulong.max)
             conn.contentLength = sz;
         conn.perform();
@@ -2264,7 +2264,7 @@ decodeString(Char = char)(const(ubyte)[] data,
     size_t charsDecoded = 0;
     while (data.length && charsDecoded < maxChars)
     {
-        dchar dc = scheme.safeDecode(data);
+        immutable dchar dc = scheme.safeDecode(data);
         if (dc == INVALID_SEQUENCE)
         {
             return typeof(return)(size_t.max, cast(Char[]) null);
@@ -2310,7 +2310,7 @@ private bool decodeLineInto(Terminator, Char = char)(ref const(ubyte)[] basesrc,
                      4 : basesrc.length + src.length;
         basesrc.length = len;
 
-        dchar dc = scheme.safeDecode(basesrc);
+        immutable dchar dc = scheme.safeDecode(basesrc);
         if (dc == INVALID_SEQUENCE)
         {
             enforce!CurlException(len != 4, "Invalid code sequence");
diff --git a/std/uri.d b/std/uri.d
index ffd12c94e..f05d7cc16 100644
--- a/std/uri.d
+++ b/std/uri.d
@@ -65,7 +65,7 @@ private immutable ubyte[128] uri_flags =      // indexed by character
         return uflags;
     })();
 
-private string URI_Encode(dstring string, uint unescapedSet)
+private string URI_Encode(dstring str, uint unescapedSet)
 {
     import core.exception : OutOfMemoryError;
     import core.stdc.stdlib : alloca;
@@ -81,7 +81,7 @@ private string URI_Encode(dstring string, uint unescapedSet)
     uint Rlen;
     uint Rsize; // alloc'd size
 
-    auto len = string.length;
+    immutable len = str.length;
 
     R = buffer.ptr;
     Rsize = buffer.length;
@@ -89,7 +89,7 @@ private string URI_Encode(dstring string, uint unescapedSet)
 
     for (k = 0; k != len; k++)
     {
-        C = string[k];
+        C = str[k];
         // if (C in unescapedSet)
         if (C < uri_flags.length && uri_flags[C] & unescapedSet)
         {
@@ -209,7 +209,7 @@ if (isSomeChar!Char)
     dchar* R;
     uint Rlen;
 
-    auto len = uri.length;
+    immutable len = uri.length;
     auto s = uri.ptr;
 
     // Preallocate result buffer R guaranteed to be large enough for result
@@ -290,7 +290,7 @@ if (isSomeChar!Char)
         if (C < uri_flags.length && uri_flags[C] & reservedSet)
         {
             // R ~= s[start .. k + 1];
-            int width = (k + 1) - start;
+            immutable width = (k + 1) - start;
             for (int ii = 0; ii < width; ii++)
                 R[Rlen + ii] = s[start + ii];
             Rlen += width;
diff --git a/std/uuid.d b/std/uuid.d
index 3e2703773..879a99215 100644
--- a/std/uuid.d
+++ b/std/uuid.d
@@ -528,7 +528,7 @@ public struct UUID
         {
             //variant is stored in octet 7
             //which is index 8, since indexes count backwards
-            auto octet7 = data[8]; //octet 7 is array index 8
+            immutable octet7 = data[8]; //octet 7 is array index 8
 
             if ((octet7 & 0x80) == 0x00) //0b0xxxxxxx
                 return Variant.ncs;
@@ -589,7 +589,7 @@ public struct UUID
         {
             //version is stored in octet 9
             //which is index 6, since indexes count backwards
-            auto octet9 = data[6];
+            immutable octet9 = data[6];
             if ((octet9 & 0xF0) == 0x10)
                 return Version.timeBased;
             else if ((octet9 & 0xF0) == 0x20)
@@ -643,7 +643,7 @@ public struct UUID
          */
         @safe pure nothrow @nogc void swap(ref UUID rhs)
         {
-            auto bck = data;
+            immutable bck = data;
             data = rhs.data;
             rhs.data = bck;
         }
@@ -1378,7 +1378,7 @@ if (isInputRange!Range
 
     parseLoop: while (!uuidRange.empty)
     {
-        dchar character = uuidRange.front;
+        immutable character = uuidRange.front;
 
         if (character == '-')
         {