diff --git a/dcalc/DmpCeff.cc b/dcalc/DmpCeff.cc
index 29f4ce4a..cc4bbca5 100644
--- a/dcalc/DmpCeff.cc
+++ b/dcalc/DmpCeff.cc
@@ -25,7 +25,7 @@
 #include "DmpCeff.hh"
 
 #include <algorithm> // abs, min
-#include <math.h>    // sqrt
+#include <cmath>    // sqrt, log
 
 #include "Report.hh"
 #include "Debug.hh"
@@ -43,6 +43,9 @@ namespace sta {
 
 using std::abs;
 using std::min;
+using std::max;
+using std::sqrt;
+using std::log;
 
 // Tolerance (as a scale of value) for driver parameters (Ceff, delta t, t0).
 static const double driver_param_tol = .01;
@@ -263,6 +266,7 @@ protected:
   // Load rspf elmore delay.
   double elmore_;
   double p3_;
+  double elmore_slew_factor_;
 
 private:
   virtual double dvl0dt(double t) = 0;
@@ -320,6 +324,7 @@ DmpAlg::init(const LibertyLibrary *drvr_library,
   vl_ = drvr_library->slewLowerThreshold(rf);
   vh_ = drvr_library->slewUpperThreshold(rf);
   slew_derate_ = drvr_library->slewDerateFromLibrary();
+  elmore_slew_factor_ = log(vh_) - log(vl_);
 }
 
 // Find Ceff, delta_t and t0 for the driver.
@@ -608,7 +613,9 @@ DmpAlg::loadDelaySlew(const Pin *,
     else {
       // Failed - use elmore delay and driver slew.
       delay = static_cast<float>(elmore_);
-      slew = static_cast<float>(gate_slew_);
+      // solve v=1-exp(-t/rc) for t, elmore_slew_factor_ = t(vh) - t(vl)
+      // slew = elmore * (log(vh_) - log(vl_))
+      slew = static_cast<float>(gate_slew_ + elmore * elmore_slew_factor_);
     }
   }
 }