diff --git a/common/nextpnr.h b/common/nextpnr.h
index f49b982e..c87a98d9 100644
--- a/common/nextpnr.h
+++ b/common/nextpnr.h
@@ -472,7 +472,7 @@ struct Context : Arch, DeterministicRNG
     bool force = false;
     bool timing_driven = true;
     float target_freq = 12e6;
-    bool user_freq = false;
+    bool auto_freq = false;
     int slack_redist_iter = 0;
 
     Context(ArchArgs args) : Arch(args) {}
diff --git a/common/timing.cc b/common/timing.cc
index 0178a4a9..c046c76f 100644
--- a/common/timing.cc
+++ b/common/timing.cc
@@ -147,7 +147,7 @@ void assign_budget(Context *ctx, bool quiet)
 {
     if (!quiet) {
         log_break();
-        log_info("Annotating ports with timing budgets\n");
+        log_info("Annotating ports with timing budgets for target frequency %.2f MHz\n", ctx->target_freq/1e6);
     }
 
     Timing timing(ctx, true /* update */);
@@ -157,7 +157,7 @@ void assign_budget(Context *ctx, bool quiet)
         for (auto &net : ctx->nets) {
             for (auto &user : net.second->users) {
                 // Post-update check
-                if (ctx->user_freq && user.budget < 0)
+                if (!ctx->auto_freq && user.budget < 0)
                     log_warning("port %s.%s, connected to net '%s', has negative "
                                 "timing budget of %fns\n",
                                 user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
@@ -174,7 +174,7 @@ void assign_budget(Context *ctx, bool quiet)
     // For slack redistribution, if user has not specified a frequency
     //   dynamically adjust the target frequency to be the currently
     //   achieved maximum
-    if (!ctx->user_freq && ctx->slack_redist_iter > 0) {
+    if (ctx->auto_freq && ctx->slack_redist_iter > 0) {
         delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
         ctx->target_freq = 1e12 / (default_slack - timing.min_slack);
         if (ctx->verbose)
diff --git a/ecp5/main.cc b/ecp5/main.cc
index f40a5e61..dac7a635 100644
--- a/ecp5/main.cc
+++ b/ecp5/main.cc
@@ -162,12 +162,8 @@ int main(int argc, char *argv[])
 
             if (!ctx->pack() && !ctx->force)
                 log_error("Packing design failed.\n");
-            if (vm.count("freq")) {
+            if (vm.count("freq"))
                 ctx->target_freq = vm["freq"].as<double>() * 1e6;
-                ctx->user_freq = true;
-            } else {
-                log_warning("Target frequency not specified. Will optimise for max frequency.\n");
-            }
             assign_budget(ctx.get());
             ctx->check();
             print_utilisation(ctx.get());
diff --git a/ice40/main.cc b/ice40/main.cc
index 37e18215..46cdce71 100644
--- a/ice40/main.cc
+++ b/ice40/main.cc
@@ -319,6 +319,13 @@ int main(int argc, char *argv[])
 
         if (vm.count("slack_redist_iter")) {
             ctx->slack_redist_iter = vm["slack_redist_iter"].as<int>();
+            if (vm.count("freq") && vm["freq"].as<double>() == 0) {
+                ctx->auto_freq = true;
+#ifndef NO_GUI
+                if (!vm.count("gui"))
+#endif
+                    log_warning("Target frequency not specified. Will optimise for max frequency.\n");
+            }
         }
 
         if (vm.count("cstrweight")) {
@@ -385,13 +392,9 @@ int main(int argc, char *argv[])
         }
 
         if (vm.count("freq")) {
-            ctx->target_freq = vm["freq"].as<double>() * 1e6;
-            ctx->user_freq = true;
-        } else {
-#ifndef NO_GUI
-            if (!vm.count("gui"))
-#endif
-                log_warning("Target frequency not specified. Will optimise for max frequency.\n");
+            auto freq = vm["freq"].as<double>();
+            if (freq > 0)
+                ctx->target_freq = freq * 1e6;
         }
 
         ctx->timing_driven = true;