diff --git a/bin/wsim b/bin/wsim
index 88b0dd6c8..38213a332 100755
--- a/bin/wsim
+++ b/bin/wsim
@@ -86,11 +86,12 @@ if (args.tb == "testbench_fp"):
 # if lockstep is enabled, then we need to pass the Imperas lockstep arguments
 if(int(args.locksteplog) >= 1): EnableLog = 1
 else: EnableLog = 0
-if((args.lockstep or args.lockstepverbose or args.fcov or args.fcovimp) and args.sim == "questa"):
-    prefix = "IMPERAS_TOOLS=" + WALLY + "/config/"+args.config+"/imperas.ic"
-    prefix = "MTI_VCO_MODE=64 " + prefix
-else:
-    prefix = ""
+prefix = ""
+if (args.lockstep or args.lockstepverbose or args.fcov or args.fcovimp):
+   if (args.sim == "questa" or args.sim == "vcs"):
+        prefix = "IMPERAS_TOOLS=" + WALLY + "/config/"+args.config+"/imperas.ic"
+   if (args.sim == "questa"):
+        prefix = "MTI_VCO_MODE=64 " + prefix
 
 if (args.lockstep or args.lockstepverbose):
     if(args.locksteplog != 0): ImperasPlusArgs = " +IDV_TRACE2LOG=" + str(EnableLog) + " +IDV_TRACE2LOG_AFTER=" + str(args.locksteplog)