diff --git a/asm/nasm.c b/asm/nasm.c
index 05eaf74ab..e22c220c1 100644
--- a/asm/nasm.c
+++ b/asm/nasm.c
@@ -112,7 +112,6 @@ static unsigned int operating_mode;
 /* Dependency flags */
 static bool depend_emit_phony = false;
 static bool depend_missing_ok = false;
-static char *depend_target = NULL;
 struct strlist *depend_list;
 
 static inline bool terminate_after_phase(void)
@@ -460,7 +459,7 @@ static void emit_dependencies(struct strlist *list)
         deps = stdout;
     }
 
-    linepos = fprintf(deps, "%s :", depend_target);
+    linepos = fprintf(deps, "%s :", get_filename(FN_DEPEND_TARGET));
     strlist_for_each(l, list) {
         char *file = quote_for_make(l->str);
         len = strlen(file);
@@ -714,10 +713,15 @@ int main(int argc, char **argv)
     fix_dependfile_name();
     fix_outfile_name();
 
-    depend_list = (operating_mode & OP_DEPEND) ? strlist_alloc(true) : NULL;
+    if (operating_mode & OP_DEPEND) {
+        depend_list = strlist_alloc(true);
 
-    if (!depend_target)
-        depend_target = quote_for_make(get_filename(FN_OUTFILE));
+        if (!get_filename(FN_DEPEND_TARGET))
+            set_filename(FN_DEPEND_TARGET,
+                         quote_for_make(get_filename(FN_OUTFILE)));
+    } else {
+        depend_list = NULL;
+    }
 
     reset_global_defaults(cmd_sb);
 
@@ -842,7 +846,6 @@ int main(int argc, char **argv)
     src_free();
     strlist_free(&include_path);
     cleanup_filenames();
-    nasm_free(depend_target);
 
     return terminate_after_phase();
 }
@@ -1349,11 +1352,11 @@ static bool process_arg(char *p, char *q, int pass)
                     advance = true;
                     break;
                 case 'T':
-                    nasm_strdupto(&depend_target, q);
+                    copy_filename(FN_DEPEND_TARGET, q);
                     advance = true;
                     break;
                 case 'Q':
-                    nasm_strto(&depend_target, quote_for_make(q));
+                    set_filename(FN_DEPEND_TARGET, quote_for_make(q));
                     advance = true;
                     break;
                 case 'W':
diff --git a/common/files.c b/common/files.c
index 3bab04ed2..17a227fc4 100644
--- a/common/files.c
+++ b/common/files.c
@@ -6,13 +6,20 @@
 #include "files.h"
 #include "error.h"
 
+/* These must match the constants in "files.h" */
 static const char * const filename_names[FN_NFILES] = {
     "input",
-    "mapped-input",
+
     "output",
     "error",
     "list",
-    "dependency"
+    "dependency",
+    "map",
+
+    NULL,                       /* End of "real" filenames */
+
+    "debug mapped input",
+    "make mapped output"
 };
 
 const char *_filenames[FN_NFILES];
@@ -40,17 +47,20 @@ const char *set_filename(enum filenames fn, char *src)
 
 void check_overwrite_files(void)
 {
-    enum filenames fn;
-    const char *inname = get_filename(FN_INFILE);
+    enum filenames fi, fo;      /* No fie or fum */
 
-    if (!inname)
-        return;
+    for (fi = FN_INFILE; fi < FN_OUTFILE; fi++) {
+        const char *inname = get_filename(fi);
 
-    for (fn = FN_INFILE+2; fn < FN_NFILES; fn++) {
-        const char *outname = get_filename(fn);
-        if (outname && !nasm_compare_paths(inname, outname)) {
-            nasm_fatal("%s file would overwrite input file",
-                       filename_names[fn]);
+        if (!inname)
+            continue;
+
+        for (fo = FN_OUTFILE; fo < FN_NFILES_REAL; fo++) {
+            const char *outname = get_filename(fo);
+            if (outname && !nasm_compare_paths(inname, outname)) {
+                nasm_nonfatal("%s file would overwrite %s file `%s'",
+                              filename_names[fo], filename_names[fi], inname);
+            }
         }
     }
 }
diff --git a/include/files.h b/include/files.h
index 92dd62dad..c20221aec 100644
--- a/include/files.h
+++ b/include/files.h
@@ -10,17 +10,35 @@
 /*
  * Primary file names set on the command line etc.
  * Wrapped in accessors to make them as constant as possible.
+ *
+ * The order of the sections in this enum is critical!
  */
 enum filenames {
-    /* These two entries must be first, in this order */
-    FN_INFILE,                  /* Primary input file */
-    FN_MAPPED_INFILE,           /* Debug mapped input file */
-    FN_OUTFILE,                 /* Primary output file */
+    /* Input filenames. FN_INFILE MUST be the first entry. */
+    FN_INFILE,                  /* Primary input file - MUST BE FIRST */
 
+    /*
+     * Section: Output filenames.
+     * FN_OUTFILE MUST be the first entry.
+     */
+    FN_OUTFILE,                 /* Primary output file - MUST BE FIRST */
     FN_ERRFILE,                 /* Error message file */
     FN_LISTFILE,                /* Listing file */
     FN_DEPENDFILE,              /* Dependency file */
     FN_MAPFILE,                 /* Map file (outbin) */
+
+    /* Total number of "real" filenames. */
+    FN_NFILES_REAL,
+
+    /*
+     * Section: Virtual filenames.
+     * Strings that don't necessarily correspond directly to paths
+     * in the host filesystem.
+     */
+    FN_MAPPED_INFILE,           /* Debug mapped input file name */
+    FN_DEPEND_TARGET,           /* Output target name per -MF, -MD, -MQ */
+
+    /* Total fixed filename count */
     FN_NFILES
 };