diff --git a/src/odoors/ODEmu.c b/src/odoors/ODEmu.c
index 501881e20dadfe88710dfa5664d24d74c84b6fcc..a75416184237ae3051d3f6d316bcaa8ed3f21ee7 100644
--- a/src/odoors/ODEmu.c
+++ b/src/odoors/ODEmu.c
@@ -1001,7 +1001,7 @@ static FILE *ODEmulateFindCompatFile(const char *pszBaseName, INT *pnLevel)
  *
  *     Return: void
  */
-ODAPIDEF void ODCALL od_disp_emu(char *pszToDisplay, BOOL bRemoteEcho)
+ODAPIDEF void ODCALL od_disp_emu(const char *pszToDisplay, BOOL bRemoteEcho)
 {
    BOOL bTranslateRemote;
 
diff --git a/src/odoors/ODMulti.c b/src/odoors/ODMulti.c
index a81c4822f46eba8b781be850b1aabe84edcc1fac..1420959ed60c9746bdaae6c0496b0b2af52031fa 100644
--- a/src/odoors/ODMulti.c
+++ b/src/odoors/ODMulti.c
@@ -108,7 +108,7 @@ ODAPIDEF void ODCALL ODMPSEnable(void)
  *
  *     Return: TRUE on success, or FALSE on failure.
  */
-ODAPIDEF BOOL ODCALL od_set_personality(char *pszName)
+ODAPIDEF BOOL ODCALL od_set_personality(const char *pszName)
 {
 #ifdef OD_TEXTMODE
    BYTE btNewPersonality;
@@ -213,7 +213,7 @@ ODAPIDEF BOOL ODCALL od_set_personality(char *pszName)
  *
  *     Return: TRUE on success or FALSE on failure.
  */
-ODAPIDEF BOOL ODCALL od_add_personality(char *pszName, BYTE btOutputTop,
+ODAPIDEF BOOL ODCALL od_add_personality(const char *pszName, BYTE btOutputTop,
    BYTE btOutputBottom, OD_PERSONALITY_PROC *pfPerFunc)
 {
    /* Log function entry if running in trace mode */
diff --git a/src/odoors/ODSpawn.c b/src/odoors/ODSpawn.c
index 18083b6eed335d8caa76fee0eb1112cc9b598817..81f6bc3f6f58c8a748b86ed0c55c385e38193c35 100644
--- a/src/odoors/ODSpawn.c
+++ b/src/odoors/ODSpawn.c
@@ -172,7 +172,7 @@ int _spawnvpe(int nModeFlag, char *pszPath, char *papszArgs[],
  *
  *     Return: TRUE on success, or FALSE on failure.
  */
-ODAPIDEF BOOL ODCALL od_spawn(char *pszCommandLine)
+ODAPIDEF BOOL ODCALL od_spawn(const char *pszCommandLine)
 {
 #ifdef ODPLAT_DOS
    char *apszArgs[4];
diff --git a/src/odoors/OpenDoor.h b/src/odoors/OpenDoor.h
index a7c2bbe91f03f62ad109e623496ba0709987f10d..3091d70e08540834021c0d6901ffebdeb2651ea3 100644
--- a/src/odoors/OpenDoor.h
+++ b/src/odoors/OpenDoor.h
@@ -948,7 +948,7 @@ od_control;
  *    od_sleep()              - Yield to other processes
  *    od_control_get()        - Returns a pointer to the od_control structure.
  */
-ODAPIDEF BOOL ODCALL   od_add_personality(char *pszName, BYTE btOutputTop,
+ODAPIDEF BOOL ODCALL   od_add_personality(const char *pszName, BYTE btOutputTop,
                           BYTE btOutputBottom,
                           OD_PERSONALITY_PROC *pfPerFunc);
 ODAPIDEF void ODCALL   od_autodetect(INT nFlags);
@@ -960,7 +960,7 @@ ODAPIDEF void ODCALL   od_clr_scr(void);
 ODAPIDEF BYTE ODCALL   od_color_config(char *pszColorDesc);
 ODAPIDEF tODControl *  ODCALL od_control_get(void);
 ODAPIDEF void ODCALL   od_disp(char *pachBuffer, INT nSize, BOOL bLocalEcho);
-ODAPIDEF void ODCALL   od_disp_emu(char *pszToDisplay, BOOL bRemoteEcho);
+ODAPIDEF void ODCALL   od_disp_emu(const char *pszToDisplay, BOOL bRemoteEcho);
 ODAPIDEF void ODCALL   od_disp_str(const char *pszToDisplay);
 ODAPIDEF BOOL ODCALL   od_draw_box(BYTE btLeft, BYTE btTop, BYTE btRight,
                           BYTE btBottom);
@@ -1011,10 +1011,10 @@ ODAPIDEF void ODCALL   od_set_attrib(INT nColour);
 ODAPIDEF void ODCALL   od_set_color(INT nForeground, INT nBackground);
 ODAPIDEF void ODCALL   od_set_cursor(INT nRow, INT nColumn);
 ODAPIDEF void ODCALL   od_set_dtr(BOOL bHigh);
-ODAPIDEF BOOL ODCALL   od_set_personality(char *pszName);
+ODAPIDEF BOOL ODCALL   od_set_personality(const char *pszName);
 ODAPIDEF void ODCALL   od_set_statusline(INT nSetting);
 ODAPIDEF void ODCALL   od_sleep(tODMilliSec Milliseconds);
-ODAPIDEF BOOL ODCALL   od_spawn(char *pszCommandLine);
+ODAPIDEF BOOL ODCALL   od_spawn(const char *pszCommandLine);
 ODAPIDEF INT16 ODCALL  od_spawnvpe(INT16 nModeFlag, char *pszPath,
                           char *papszArg[], char *papszEnv[]);
 ODAPIDEF void * ODCALL od_window_create(INT nLeft, INT nTop, INT nRight,