diff --git a/pentrc/energy.f90 b/pentrc/energy.f90
index ba1f9f1a7..e0a70b14e 100644
--- a/pentrc/energy.f90
+++ b/pentrc/energy.f90
@@ -69,7 +69,15 @@ module energy_integration
             energy_wb,&
             energy_nuk,&
             energy_leff
-    !$omp threadprivate(energy_wn,energy_wt,energy_we,energy_wd,energy_wb,&
+    ! energy_imaxis selects the integration contour inside xintgrnd, and
+    ! xintgrl_lsode flips it between its imaginary-axis and real-axis legs.  It
+    ! is per-integration state exactly like the frequencies below it, so it must
+    ! be threadprivate too: shared, one thread's imaginary leg silently switches
+    ! another thread's integrand from x + i*ximag to i*x, turning exp(-cx) from
+    ! a decaying exponential into an oscillation and injecting values orders of
+    ! magnitude too large into the pitch integrand.
+    !$omp threadprivate(energy_imaxis,&
+    !$omp&              energy_wn,energy_wt,energy_we,energy_wd,energy_wb,&
     !$omp&              energy_nuk,energy_leff,energy_n)
 
     type record
diff --git a/pentrc/pentrc_interface.f90 b/pentrc/pentrc_interface.f90
index 8b890b4d9..35571f139 100644
--- a/pentrc/pentrc_interface.f90
+++ b/pentrc/pentrc_interface.f90
@@ -111,9 +111,15 @@ module pentrc_interface
         pentrc_threads = 0,&
         openmp_threads = 0
 
+    !> How much tighter the energy integration is than the pitch integration
+    !> when atol_x/rtol_x are left at their derive-me default.
+    real(r8), parameter :: nested_tolerance_margin = 1e-2
+
     real(r8) ::    &
         atol_xlmda=1e-6, &
         rtol_xlmda=1e-3, &
+        atol_x=-1, &
+        rtol_x=-1, &
         nfac=1.0,  &
         tfac=1.0,  &
         wefac=1.0, &
@@ -148,7 +154,8 @@ module pentrc_interface
             jac_in, jsurf_in, tmag_in, power_bin, power_bpin, power_rin, power_rcin
 
     namelist/pent_control/nfac, tfac, wefac, wdfac, wpfac, nufac, divxfac, &
-            atol_xlmda, rtol_xlmda, atol_psi, rtol_psi, nlmda, ntheta, ximag, xmax, psilims, &
+            atol_xlmda, rtol_xlmda, atol_x, rtol_x, atol_psi, rtol_psi, &
+            nlmda, ntheta, ximag, xmax, psilims, &
             use_classic_splines,pentrc_threads,openmp_threads,force_xialpha
 
     namelist/pent_output/moment, output_ascii, output_netcdf, &
@@ -221,8 +228,7 @@ subroutine initialize_pentrc(op_kin,op_deq,op_peq)
         !if(any(psilim/=0)) print *, "!! WARNING: psilim has been deprecated. Use psilims."
 
         ! distribute some simplified inputs to module circles
-        xatol = atol_xlmda
-        xrtol = rtol_xlmda
+        call set_nested_tolerances
         xnufac= nufac
         xnutype= nutype
         xf0type= f0type
@@ -279,8 +285,7 @@ subroutine get_pentrc(get_nl,get_zi,get_mi,get_wdfac,get_divxfac,&
         close(i)
         
         ! distribute inputs to PENTRC module circles
-        xatol = atol_xlmda
-        xrtol = rtol_xlmda
+        call set_nested_tolerances
         xnufac= nufac
         xnutype= nutype
         xf0type= f0type 
@@ -307,6 +312,37 @@ subroutine get_pentrc(get_nl,get_zi,get_mi,get_wdfac,get_divxfac,&
         
     end subroutine get_pentrc
     
+
+    !=======================================================================
+    subroutine set_nested_tolerances
+    !-----------------------------------------------------------------------
+    !*DESCRIPTION:
+    !   Give the energy integration its own, tighter tolerances.
+    !
+    !   The pitch integral's integrand IS the energy integral, so this is a
+    !   nested adaptive quadrature.  With one tolerance for both, the outer
+    !   integrator chases the inner one's quadrature error, which is not a
+    !   smooth function of lambda; LSODE then shrinks its step without bound
+    !   and stops with "too many steps in lambda required".
+    !
+    !   Negative atol_x/rtol_x, the default, means "derive from the pitch
+    !   tolerances".  A deck may set them explicitly, including back to the
+    !   old aliased values.
+    !-----------------------------------------------------------------------
+        implicit none
+        if(atol_x < 0) then
+            xatol = atol_xlmda * nested_tolerance_margin
+        else
+            xatol = atol_x
+        endif
+        if(rtol_x < 0) then
+            xrtol = rtol_xlmda * nested_tolerance_margin
+        else
+            xrtol = rtol_x
+        endif
+    end subroutine set_nested_tolerances
+
+
 end module pentrc_interface