diff --git a/src/posix/cocoa/i_system.mm b/src/posix/cocoa/i_system.mm
index 7b7c6dcc2c..3390d65ba0 100644
--- a/src/posix/cocoa/i_system.mm
+++ b/src/posix/cocoa/i_system.mm
@@ -73,18 +73,6 @@ ticcmd_t* I_BaseTiccmd()
 }
 
 
-void I_WaitVBL(const int count)
-{
-    // I_WaitVBL is never used to actually synchronize to the
-    // vertical blank. Instead, it's used for delay purposes.
-    struct timespec delay, rem;
-    delay.tv_sec = count / 70;
-    /* Avoid overflow. Microsec res should be good enough. */
-    delay.tv_nsec = (count%70)*1000000/70 * 1000;
-    while(nanosleep(&delay, &rem) == -1 && errno == EINTR)
-        delay = rem;
-}
-
 
 //
 // SetLanguageIDs
diff --git a/src/posix/i_system.h b/src/posix/i_system.h
index 7e9f83939c..7f468f1432 100644
--- a/src/posix/i_system.h
+++ b/src/posix/i_system.h
@@ -57,22 +57,6 @@ extern void SetLanguageIDs ();
 // Called by DoomMain.
 void I_Init (void);
 
-// Called by D_DoomLoop,
-// returns current time in tics.
-extern int (*I_GetTime) (bool saveMS);
-
-// like I_GetTime, except it waits for a new tic before returning
-extern int (*I_WaitForTic) (int);
-
-// Freezes tic counting temporarily. While frozen, calls to I_GetTime()
-// will always return the same value. This does not affect I_MSTime().
-// You must also not call I_WaitForTic() while freezing time, since the
-// tic will never arrive (unless it's the current one).
-extern void (*I_FreezeTime) (bool frozen);
-
-double I_GetTimeFrac (uint32_t *ms);
-void I_SetFrameTime();
-
 // Return a seed value for the RNG.
 unsigned int I_MakeRNGSeed();