diff --git a/source/numem/collections/vector.d b/source/numem/collections/vector.d
index ff9fa9d..414c737 100644
--- a/source/numem/collections/vector.d
+++ b/source/numem/collections/vector.d
@@ -572,7 +572,7 @@ public:
         D slices are short lived and may end up pointing to invalid memory if their string is modified.
     */
     @trusted
-    T[] opSlice(size_t dim = 0)(size_t start, size_t end) {
+    inout(T)[] opSlice(size_t dim = 0)(size_t start, size_t end) inout {
         return memory[start..end];
     }
 
diff --git a/source/numem/core/env.d b/source/numem/core/env.d
index 543e1d3..c12fbc5 100644
--- a/source/numem/core/env.d
+++ b/source/numem/core/env.d
@@ -15,6 +15,7 @@ import numem.core.memory;
 
 version(Windows) import core.sys.windows.winbase : GetEnvironmentVariableW, SetEnvironmentVariableW;
 else import core.sys.posix.stdlib : setenv, getenv;
+import core.sys.windows.raserror;
 
 @nogc:
 
@@ -26,7 +27,7 @@ struct Environment {
 private:
     static nstring get(const(char)* key) {
         version(Windows) {
-            auto utf16k = key.toUTF16;
+            auto utf16k = key.fromStringz.toUTF16;
 
             // Try getting the size of the env var.
             // if this fails, the env var is probably empty.
@@ -37,7 +38,7 @@ private:
             // Windows includes the null terminator, but n*string does too
             // so to not have 2 null terminators, subtract 1.
             nwstring envstr = nwstring(bufSize-1);
-            bufSize = GetEnvironmentVariableW(utf16k.ptr, envstr.ptr, envstr.length+1);
+            bufSize = GetEnvironmentVariableW(utf16k.ptr, cast(wchar*)envstr.ptr, cast(uint)(envstr.length+1));
 
             nogc_delete(utf16k);
             return envstr.toUTF8;
@@ -48,9 +49,9 @@ private:
 
     static bool set(const(char)* key, nstring value) {
         version(Windows) {
-            auto utf16k = key.toUTF16();
+            auto utf16k = key.fromStringz.toUTF16();
             auto utf16v = value.toUTF16();
-            return SetEnvironmentVariableW(utf16k.ptr, utf16v.ptr);
+            return cast(bool)SetEnvironmentVariableW(utf16k.ptr, utf16v.ptr);
         } else {
             return setenv(key, value.ptr, 1) == 0;
         }
diff --git a/source/numem/string.d b/source/numem/string.d
index 7bd09fe..4faf5ed 100644
--- a/source/numem/string.d
+++ b/source/numem/string.d
@@ -416,19 +416,16 @@ public:
     }
 
     /**
-        Tests equality between nstrings
+        Tests equality between strings
     */
     @trusted
-    bool opEquals(R)(R other) if(is(R == basic_string!T)) {
-        return this.length == other.length && this[0..$] == other[0..$];
-    }
-
-    /**
-        Tests equality between nstrings
-    */
-    @trusted
-    bool opEquals(R)(R other) if(is(R == immutable(T)[])) {
-        return this.size == other.length && this[0..$-1] == other[0..$];
+    bool opEquals(R)(ref auto inout R other) inout if (isSomeString!R) {
+        static if (isSomeCString!R)
+            size_t len = cstrlen(other);
+        else
+            size_t len = other.length;
+        
+        return this.length == len && this.vec_[0..len] == other[0..len];
     }
 
     /**
diff --git a/source/numem/text/unicode/package.d b/source/numem/text/unicode/package.d
index 8e95096..f85e762 100644
--- a/source/numem/text/unicode/package.d
+++ b/source/numem/text/unicode/package.d
@@ -110,8 +110,8 @@ T encode(T)(ref auto UnicodeSequence seq, bool addBOM = false) if (isSomeNString
 
     This will always create a copy.
 */
-ref auto toUTF8(FromT)(ref auto T from) if (isSomeSafeString!T) {
-    static if (StringCharSize!T == 1)
+ref auto toUTF8(FromT)(ref auto FromT from) if (isSomeSafeString!FromT) {
+    static if (StringCharSize!FromT == 1)
         return nstring(from);
     else
         return encode!nstring(decode(from, true), false);
@@ -122,8 +122,8 @@ ref auto toUTF8(FromT)(ref auto T from) if (isSomeSafeString!T) {
 
     This will always create a copy.
 */
-ref auto toUTF16(FromT)(ref auto T from, bool addBOM = false) if (isSomeSafeString!T) {
-    static if (StringCharSize!T == 2)
+ref auto toUTF16(FromT)(ref auto FromT from, bool addBOM = false) if (isSomeSafeString!FromT) {
+    static if (StringCharSize!FromT == 2)
         return nwstring(from);
     else
         return encode!nwstring(decode(from, true), addBOM);
@@ -134,8 +134,8 @@ ref auto toUTF16(FromT)(ref auto T from, bool addBOM = false) if (isSomeSafeStri
 
     This will always create a copy.
 */
-ref auto toUTF32(FromT)(ref auto T from, bool addBOM = false) if (isSomeSafeString!T) {
-    static if (StringCharSize!T == 2)
+ref auto toUTF32(FromT)(ref auto FromT from, bool addBOM = false) if (isSomeSafeString!FromT) {
+    static if (StringCharSize!FromT == 2)
         return ndstring(from);
     else
         return encode!ndstring(decode(from, true), addBOM);
diff --git a/source/numem/text/unicode/utf8.d b/source/numem/text/unicode/utf8.d
index cd55e8d..295b17a 100644
--- a/source/numem/text/unicode/utf8.d
+++ b/source/numem/text/unicode/utf8.d
@@ -290,9 +290,10 @@ UnicodeSequence decode(inout(char)[] str) {
 
         // Validate length, add FFFD if invalid.
         size_t clen = str[i].getLength();
-        if (clen >= i+str.length || clen == 0) {
+        if (i+clen > str.length || clen == 0) {
             code ~= unicodeReplacementCharacter;
             i++;
+            continue;
         }
 
         txt[0..clen] = str[i..i+clen];