diff --git a/compiler/src/dmd/backend/cc.d b/compiler/src/dmd/backend/cc.d
index 49b14db8fd7..f9c033abacd 100644
--- a/compiler/src/dmd/backend/cc.d
+++ b/compiler/src/dmd/backend/cc.d
@@ -1475,8 +1475,8 @@ struct dt_t
         targ_size_t DTazeros;           // DTazeros,DTcommon,DTsymsize
         struct                          // DTabytes
         {
-            byte *DTpbytes;             // pointer to the bytes
-            uint DTnbytes;              // # of bytes
+            byte* DTpbytes;             // pointer to the bytes
+            size_t DTnbytes;            // # of bytes
             int DTseg;                  // segment it went into
             targ_size_t DTabytes;       // offset of abytes for DTabytes
         }
diff --git a/compiler/src/dmd/backend/dout.d b/compiler/src/dmd/backend/dout.d
index 17f6ad1d28d..128a986a04b 100644
--- a/compiler/src/dmd/backend/dout.d
+++ b/compiler/src/dmd/backend/dout.d
@@ -592,7 +592,7 @@ Symbol *out_string_literal(const(char)* str, uint len, uint sz)
     }
 
     auto dtb = DtBuilder(0);
-    dtb.nbytes(cast(uint)(len * sz), str);
+    dtb.nbytes(str[0 .. len * sz]);
     dtb.nzeros(cast(uint)sz);       // include terminating 0
     s.Sdt = dtb.finish();
     s.Sfl = FLdata;
diff --git a/compiler/src/dmd/backend/dt.d b/compiler/src/dmd/backend/dt.d
index b728baf58a5..54d09c88aa8 100644
--- a/compiler/src/dmd/backend/dt.d
+++ b/compiler/src/dmd/backend/dt.d
@@ -252,37 +252,44 @@ nothrow:
     /***********************
      * Append data represented by ptr[0..size]
      */
+    void nbytes(const(char)[] ptr)
+    {
+        return nbytes(cast(const(ubyte)[]) ptr);
+    }
+
+    /// ditto
     @trusted
-    void nbytes(uint size, const(char)* ptr)
+    void nbytes(const(ubyte)[] data)
     {
-        if (!size)
+        if (!data.length)
             return;
 
         bool allZero = true;
-        foreach (i; 0 .. size)
+        foreach (i; 0 .. data.length)
         {
-            if (ptr[i] != 0)
+            if (data.ptr[i] != 0)
             {
                 allZero = false;
                 break;
             }
         }
         if (allZero)
-            return nzeros(size);
+            return nzeros(data.length);
 
         dt_t *dt;
 
-        if (size < dt_t.DTibytesMax)
-        {   dt = dt_calloc(DT_ibytes);
-            dt.DTn = cast(ubyte)size;
-            memcpy(dt.DTdata.ptr,ptr,size);
+        if (data.length < dt_t.DTibytesMax)
+        {
+            dt = dt_calloc(DT_ibytes);
+            dt.DTn = cast(ubyte)data.length;
+            memcpy(dt.DTdata.ptr, data.ptr, data.length);
         }
         else
         {
             dt = dt_calloc(DT_nbytes);
-            dt.DTnbytes = size;
-            dt.DTpbytes = cast(byte *) mem_malloc(size);
-            memcpy(dt.DTpbytes,ptr,size);
+            dt.DTnbytes = data.length;
+            dt.DTpbytes = cast(byte*) mem_malloc(data.length);
+            memcpy(dt.DTpbytes, data.ptr, data.length);
         }
 
         assert(!*pTail);
@@ -383,7 +390,7 @@ nothrow:
     /***********************
      * Write a bunch of zeros
      */
-    void nzeros(uint size)
+    void nzeros(size_t size)
     {
         if (!size)
             return;
diff --git a/compiler/src/dmd/backend/pdata.d b/compiler/src/dmd/backend/pdata.d
index 5f9f0749812..e502af5b7ee 100644
--- a/compiler/src/dmd/backend/pdata.d
+++ b/compiler/src/dmd/backend/pdata.d
@@ -273,6 +273,6 @@ static if (1)
     ui.UnwindCode[ui.CountOfCodes-1].FrameOffset = setUnwindCode(1, UWOP.PUSH_NONVOL, BP);
 
     auto dtb = DtBuilder(0);
-    dtb.nbytes(4 + ((ui.CountOfCodes + 1) & ~1) * 2,cast(char *)&ui);
+    dtb.nbytes((cast(const(ubyte*)) &ui)[0 .. 4 + ((ui.CountOfCodes + 1) & ~1) * 2]);
     return dtb.finish();
 }
diff --git a/compiler/src/dmd/glue.d b/compiler/src/dmd/glue.d
index 0a1767c39e6..76ba39b00f4 100644
--- a/compiler/src/dmd/glue.d
+++ b/compiler/src/dmd/glue.d
@@ -1430,7 +1430,7 @@ private void genObjFile(Module m, bool multiobj)
         bcov.Sfl = FLdata;
 
         auto dtb = DtBuilder(0);
-        dtb.nbytes(cast(uint)(m.covb.length * m.covb[0].sizeof), cast(char*)m.covb.ptr);
+        dtb.nbytes(cast(const(ubyte)[]) m.covb);
         bcov.Sdt = dtb.finish();
 
         outdata(bcov);
diff --git a/compiler/src/dmd/objc_glue.d b/compiler/src/dmd/objc_glue.d
index db17af93d60..a705fd0c54f 100644
--- a/compiler/src/dmd/objc_glue.d
+++ b/compiler/src/dmd/objc_glue.d
@@ -557,7 +557,7 @@ static:
 
         // create data
         auto dtb = DtBuilder(0);
-        dtb.nbytes(cast(uint) (str.length + 1), str.toStringz());
+        dtb.nbytes(str.toStringz()[0 .. str.length + 1]);
 
         // find segment
         auto seg = Segments[segment];
diff --git a/compiler/src/dmd/todt.d b/compiler/src/dmd/todt.d
index 7b7114abee8..3d04a8e40bb 100644
--- a/compiler/src/dmd/todt.d
+++ b/compiler/src/dmd/todt.d
@@ -307,7 +307,7 @@ void Expression_toDt(Expression e, ref DtBuilder dtb)
     {
         //printf("IntegerExp.toDt() %d\n", e.op);
         auto value = e.getInteger();
-        dtb.nbytes(cast(uint)e.type.size(), cast(char*) &value);
+        dtb.nbytes((cast(ubyte*) &value)[0 .. e.type.size()]);
     }
 
     void visitReal(RealExp e)
@@ -319,7 +319,7 @@ void Expression_toDt(Expression e, ref DtBuilder dtb)
             case Timaginary32:
             {
                 auto fvalue = cast(float)e.value;
-                dtb.nbytes(4, cast(char*)&fvalue);
+                dtb.nbytes((cast(ubyte*)&fvalue)[0 .. 4]);
                 break;
             }
 
@@ -327,7 +327,7 @@ void Expression_toDt(Expression e, ref DtBuilder dtb)
             case Timaginary64:
             {
                 auto dvalue = cast(double)e.value;
-                dtb.nbytes(8, cast(char*)&dvalue);
+                dtb.nbytes((cast(ubyte*)&dvalue)[0 .. 8]);
                 break;
             }
 
@@ -335,7 +335,7 @@ void Expression_toDt(Expression e, ref DtBuilder dtb)
             case Timaginary80:
             {
                 auto evalue = e.value;
-                dtb.nbytes(target.realsize - target.realpad, cast(char*)&evalue);
+                dtb.nbytes((cast(ubyte*)&evalue)[0 .. target.realsize - target.realpad]);
                 dtb.nzeros(target.realpad);
                 break;
             }
@@ -354,28 +354,28 @@ void Expression_toDt(Expression e, ref DtBuilder dtb)
             case Tcomplex32:
             {
                 auto fvalue = cast(float)creall(e.value);
-                dtb.nbytes(4, cast(char*)&fvalue);
+                dtb.nbytes((cast(ubyte*)&fvalue)[0 .. 4]);
                 fvalue = cast(float)cimagl(e.value);
-                dtb.nbytes(4, cast(char*)&fvalue);
+                dtb.nbytes((cast(ubyte*)&fvalue)[0 .. 4]);
                 break;
             }
 
             case Tcomplex64:
             {
                 auto dvalue = cast(double)creall(e.value);
-                dtb.nbytes(8, cast(char*)&dvalue);
+                dtb.nbytes((cast(ubyte*)&dvalue)[0 .. 8]);
                 dvalue = cast(double)cimagl(e.value);
-                dtb.nbytes(8, cast(char*)&dvalue);
+                dtb.nbytes((cast(ubyte*)&dvalue)[0 .. 8]);
                 break;
             }
 
             case Tcomplex80:
             {
                 auto evalue = creall(e.value);
-                dtb.nbytes(target.realsize - target.realpad, cast(char*)&evalue);
+                dtb.nbytes((cast(ubyte*)&evalue)[0 .. target.realsize - target.realpad]);
                 dtb.nzeros(target.realpad);
                 evalue = cimagl(e.value);
-                dtb.nbytes(target.realsize - target.realpad, cast(char*)&evalue);
+                dtb.nbytes((cast(ubyte*)&evalue)[0 .. target.realsize - target.realpad]);
                 dtb.nzeros(target.realpad);
                 break;
             }
@@ -435,7 +435,7 @@ void Expression_toDt(Expression e, ref DtBuilder dtb)
             {
                 auto tsa = t.isTypeSArray();
 
-                dtb.nbytes(n * e.sz, p);
+                dtb.nbytes((cast(ubyte*) p)[0 .. n * e.sz]);
                 if (tsa.dim)
                 {
                     dinteger_t dim = tsa.dim.toInteger();
@@ -855,7 +855,7 @@ private void membersToDt(AggregateDeclaration ad, ref DtBuilder dtb,
                 offset = bitByteOffset;
             }
 
-            dtb.nbytes(bitFieldSize, cast(char*)&bitFieldValue);
+            dtb.nbytes((cast(ubyte*) &bitFieldValue)[0 .. bitFieldSize]);
             offset += bitFieldSize;
             bitOffset = 0;
             bitFieldValue = 0;
@@ -1280,7 +1280,7 @@ private extern (C++) class TypeInfoDtVisitor : Visitor
         }
 
         // Put out name[] immediately following TypeInfo_Enum
-        dtb.nbytes(cast(uint)(namelen + 1), name);
+        dtb.nbytes(name[0 .. namelen + 1]);
     }
 
     override void visit(TypeInfoPointerDeclaration d)
@@ -1384,7 +1384,7 @@ private extern (C++) class TypeInfoDtVisitor : Visitor
         dtb.xoff(d.csym, Type.typeinfofunction.structsize);
 
         // Put out name[] immediately following TypeInfo_Function
-        dtb.nbytes(cast(uint)(namelen + 1), name);
+        dtb.nbytes(name[0 .. namelen + 1]);
     }
 
     override void visit(TypeInfoDelegateDeclaration d)
@@ -1408,7 +1408,7 @@ private extern (C++) class TypeInfoDtVisitor : Visitor
         dtb.xoff(d.csym, Type.typeinfodelegate.structsize);
 
         // Put out name[] immediately following TypeInfo_Delegate
-        dtb.nbytes(cast(uint)(namelen + 1), name);
+        dtb.nbytes(name[0 .. namelen + 1]);
     }
 
     override void visit(TypeInfoStructDeclaration d)
@@ -1572,7 +1572,7 @@ private extern (C++) class TypeInfoDtVisitor : Visitor
             dtb.size(0);
 
         // Put out mangledName[] immediately following TypeInfo_Struct
-        dtb.nbytes(cast(uint)(mangledNameLen + 1), mangledName);
+        dtb.nbytes(mangledName[0 .. mangledNameLen + 1]);
     }
 
     override void visit(TypeInfoClassDeclaration d)
diff --git a/compiler/src/dmd/toobj.d b/compiler/src/dmd/toobj.d
index 46cdae5d1a3..adcffcfa443 100644
--- a/compiler/src/dmd/toobj.d
+++ b/compiler/src/dmd/toobj.d
@@ -205,7 +205,7 @@ void genModuleInfo(Module m)
         m.nameoffset = dtb.length();
         const(char) *name = m.toPrettyChars();
         m.namelen = strlen(name);
-        dtb.nbytes(cast(uint)m.namelen + 1, name);
+        dtb.nbytes(name[0 .. m.namelen + 1]);
         //printf("nameoffset = x%x\n", nameoffset);
     }
 
@@ -1399,7 +1399,7 @@ Louter:
         import dmd.common.blake3;
         const hash = blake3((cast(ubyte*)name)[0 .. namelen]);
         //truncate and use the first 16 bytes only
-        dtb.nbytes(16, cast(char*)hash.ptr);
+        dtb.nbytes(hash[0 .. 16]);
     }
 
     //////////////////////////////////////////////
@@ -1465,7 +1465,7 @@ Louter:
 
     dtpatchoffset(pdtname, offset);
 
-    dtb.nbytes(cast(uint)(namelen + 1), name);
+    dtb.nbytes(name[0 .. namelen + 1]);
     const size_t namepad = -(namelen + 1) & (target.ptrsize - 1); // align
     dtb.nzeros(cast(uint)namepad);
 }
@@ -1608,7 +1608,7 @@ private void InterfaceInfoToDt(ref DtBuilder dtb, InterfaceDeclaration id)
         import dmd.common.blake3;
         const hash = blake3((cast(ubyte*)name)[0 .. namelen]);
         //only use the first 16 bytes
-        dtb.nbytes(16, cast(char*)hash.ptr);
+        dtb.nbytes(hash[0 .. 16]);
     }
 
     //////////////////////////////////////////////
@@ -1637,7 +1637,7 @@ private void InterfaceInfoToDt(ref DtBuilder dtb, InterfaceDeclaration id)
 
     dtpatchoffset(pdtname, offset);
 
-    dtb.nbytes(cast(uint)(namelen + 1), name);
+    dtb.nbytes(name[0 .. namelen + 1]);
     const size_t namepad =  -(namelen + 1) & (target.ptrsize - 1); // align
     dtb.nzeros(cast(uint)namepad);
 }