diff --git a/doc/filters.texi b/doc/filters.texi
index 3ebaef88285ff93b0d4b97c2f2cff72512efc52a..bd15b5ead4db971ddb986bbfd9c120033798428b 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -2438,7 +2438,7 @@ source. The default values of @var{width} and @var{height} are
 respectively 352 and 288 (corresponding to the CIF size format).
 
 @var{timebase} specifies an arithmetic expression representing a
-timebase. The expression can contain the constants "PI", "E", "PHI",
+timebase. The expression can contain the constant
 "AVTB" (the default timebase), and defaults to the value "AVTB".
 
 @section frei0r_src
diff --git a/libavfilter/vsrc_nullsrc.c b/libavfilter/vsrc_nullsrc.c
index c513be800d461bba064ef613351b138081ea7924..b6d35678774e9542b1f5c03717d5270f75b9aad4 100644
--- a/libavfilter/vsrc_nullsrc.c
+++ b/libavfilter/vsrc_nullsrc.c
@@ -28,17 +28,11 @@
 #include "avfilter.h"
 
 static const char *var_names[] = {
-    "E",
-    "PHI",
-    "PI",
     "AVTB",   /* default timebase 1/AV_TIME_BASE */
     NULL
 };
 
 enum var_name {
-    VAR_E,
-    VAR_PHI,
-    VAR_PI,
     VAR_AVTB,
     VAR_VARS_NB
 };
@@ -76,9 +70,6 @@ static int config_props(AVFilterLink *outlink)
     int ret;
     double res;
 
-    priv->var_values[VAR_E]    = M_E;
-    priv->var_values[VAR_PHI]  = M_PHI;
-    priv->var_values[VAR_PI]   = M_PI;
     priv->var_values[VAR_AVTB] = av_q2d(AV_TIME_BASE_Q);
 
     if ((ret = av_expr_parse_and_eval(&res, priv->tb_expr, var_names, priv->var_values,