diff --git a/src/cl65/main.c b/src/cl65/main.c
index 42126e6d7..528e64e56 100644
--- a/src/cl65/main.c
+++ b/src/cl65/main.c
@@ -122,6 +122,11 @@ static int DoAssemble   = 1;
 /* The name of the output file, NULL if none given */
 static const char* OutputName = 0;
 
+/* The path part of the output file, NULL if none given
+** or the OutputName is just a filename with no path
+** information. */
+static char *OutputDirectory = 0;
+
 /* The name of the linker configuration file if given */
 static const char* LinkerConfig = 0;
 
@@ -555,7 +560,7 @@ static void AssembleFile (const char* File, const char* TmpFile, unsigned ArgCou
         if (TmpFile) {
             ObjName = MakeFilename (TmpFile, ".o");
         } else {
-            ObjName = MakeTmpFilename (".o");
+            ObjName = MakeTmpFilename (OutputDirectory, File, ".o");
         }
         CmdSetOutput (&CA65, ObjName);
         CmdAddFile (&LD65, ObjName);
@@ -684,7 +689,7 @@ static void Compile (const char* File)
 
     if (DoAssemble) {
         /* set a temporary output file name */
-        TmpFile = MakeTmpFilename(".s");
+        TmpFile = MakeTmpFilename(OutputDirectory, File, ".s");
         CmdSetOutput (&CC65, TmpFile);
     }
 
@@ -729,7 +734,7 @@ static void CompileRes (const char* File)
     ** BEFORE adding the file
     */
     if (DoAssemble && DoLink) {
-        AsmName = MakeTmpFilename(".s");
+        AsmName = MakeTmpFilename(OutputDirectory, File, ".s");
         CmdSetAsmOutput(&GRC, AsmName);
     }
 
@@ -1623,6 +1628,7 @@ int main (int argc, char* argv [])
                 case 'o':
                     /* Name the output file */
                     OutputName = GetArg (&I, 2);
+                    OutputDirectory = GetFileDirectory(OutputName);
                     break;
 
                 case 'r':
@@ -1713,6 +1719,9 @@ int main (int argc, char* argv [])
     }
 
     RemoveTempFiles ();
+    if (OutputDirectory != NULL) {
+      xfree(OutputDirectory);
+    }
 
     /* Return an apropriate exit code */
     return EXIT_SUCCESS;
diff --git a/src/common/fname.c b/src/common/fname.c
index e67470b33..d835ee7a0 100644
--- a/src/common/fname.c
+++ b/src/common/fname.c
@@ -33,8 +33,17 @@
 
 
 
+#include <errno.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
+#include <time.h>
+
+#if defined(_MSC_VER)
+#  include <process.h>
+#else
+#  include <unistd.h>
+#endif
 
 #include "xmalloc.h"
 #include "fname.h"
@@ -93,7 +102,28 @@ const char* FindName (const char* Path)
     return Path + Len;
 }
 
+char *GetFileDirectory (const char* File)
+/* Return a copy of the path part of a File, or NULL if there is none. */
+{
+    char *Out, *P;
 
+    if (File == NULL) {
+        return NULL;
+    }
+
+    Out = xmalloc (strlen (File) + 1);
+    strcpy(Out, File);
+
+    P = (char *)FindName (Out);
+    if (P == Out) {
+        /* This is a simple filename. */
+        xfree (Out);
+        return NULL;
+    }
+    *P = '\0';
+
+    return Out;
+}
 
 char* MakeFilename (const char* Origin, const char* Ext)
 /* Make a new file name from Origin and Ext. If Origin has an extension, it
@@ -119,35 +149,22 @@ char* MakeFilename (const char* Origin, const char* Ext)
 
 
 
-char* MakeTmpFilename (const char* Ext)
-/* Make a new temporary file name from Ext.  tmpnam(3) is called
-** and Ext is appended to generate the filename.
+char* MakeTmpFilename (const char *Directory, const char *Origin, const char* Ext)
+/* Make a new temporary file name from Origin and Ext.
 ** The result is placed in a malloc'ed buffer and returned.
 */
 {
     char* Out;
-    char Buffer[L_tmpnam * 2]; /* a lazy way to ensure we have space for Ext */
+    size_t Len = 0;
 
-    /*
-    ** gcc emits the following warning here:
-    **
-    ** warning: the use of `tmpnam' is dangerous, better use `mkstemp'
-    **
-    ** however, mkstemp actually opens a file, which we do not want.
-    ** tmpfile() is unsuitable for the same reason.
-    **
-    ** we could write our own version, but then we would have to struggle
-    ** with supporting multiple build environments.
-    **
-    ** tmpnam(3) is safe here, because ca65 / cc65 / ld65 will simply clobber
-    ** an existing file, or exit if with an error if they are unable to.
-    **
-    ** gcc will also complain, if you don't use the return value from tmpnam(3)
-    */
-    strcat(tmpnam(Buffer), Ext);
-
-    Out = xmalloc (strlen (Buffer) + 1);
-    strcpy (Out, Buffer);
+    /* Allocate template */
+    if (Directory != NULL) {
+      Len = strlen (Directory);
+    }
+    Len += strlen (Origin) + strlen (".2147483648") + strlen (Ext) + 1;
+    Out = xmalloc (Len);
 
+    snprintf (Out, Len, "%s%s.%u%s", (Directory != NULL ? Directory : ""),
+                                     FindName(Origin), getpid(), Ext);
     return Out;
 }
diff --git a/src/common/fname.h b/src/common/fname.h
index 852c4ae56..ede34152d 100644
--- a/src/common/fname.h
+++ b/src/common/fname.h
@@ -52,6 +52,9 @@ const char* FindName (const char* Path);
 ** the file, the function returns Path as name.
 */
 
+char *GetFileDirectory (const char* File);
+/* Return a copy of the path part of a File, or NULL if there is none. */
+
 char* MakeFilename (const char* Origin, const char* Ext);
 /* Make a new file name from Origin and Ext. If Origin has an extension, it
 ** is removed and Ext is appended. If Origin has no extension, Ext is simply
@@ -59,9 +62,10 @@ char* MakeFilename (const char* Origin, const char* Ext);
 ** The function may be used to create "foo.o" from "foo.s".
 */
 
-char* MakeTmpFilename (const char* Ext);
-/* Make a new temporary file name from Ext.  tmpnam(3) is called
-** and Ext is appended to generate the filename.
+char* MakeTmpFilename (const char *Directory, const char *Origin, const char* Ext);
+/* Make a new temporary file name from Directory, Origin, and Ext.
+** A temporary path is generated from the Directory,
+** the Origin filename, the compiler's PID and the Extension.
 ** The result is placed in a malloc'ed buffer and returned.
 */