diff --git a/src/emu/screen.cpp b/src/emu/screen.cpp
index 5a9c055bbbb..19b0d05b6ad 100644
--- a/src/emu/screen.cpp
+++ b/src/emu/screen.cpp
@@ -683,9 +683,9 @@ void screen_device::device_validity_check(validity_checker &valid) const
 			osd_printf_error("Non-raster display cannot have a variable width\n");
 	}
 
-	// check for zero frame rate
-	if (m_refresh == 0)
-		osd_printf_error("Invalid (zero) refresh rate\n");
+	// check for invalid frame rate
+	if (m_refresh == 0 || m_refresh > ATTOSECONDS_PER_SECOND)
+		osd_printf_error("Invalid (under 1Hz) refresh rate\n");
 
 	texture_format texformat = !m_screen_update_ind16.isnull() ? TEXFORMAT_PALETTE16 : TEXFORMAT_RGB32;
 	if (m_palette.finder_tag() != finder_base::DUMMY_TAG)
diff --git a/src/frontend/mame/ui/devopt.cpp b/src/frontend/mame/ui/devopt.cpp
index cfb277127fd..c9a2c7f4360 100644
--- a/src/frontend/mame/ui/devopt.cpp
+++ b/src/frontend/mame/ui/devopt.cpp
@@ -120,13 +120,16 @@ void menu_device_config::populate_text(std::optional<text_layout> &layout, float
 				}
 				else
 				{
-					std::string hz(std::to_string(u32(screen.frame_period().as_hz() * 1'000'000 + 0.5)));
-					size_t dpos = hz.length() - 6;
-					if (dpos == 0)
-						hz.insert(dpos++, "0");
-					hz.insert(dpos, ".");
-					size_t last = hz.find_last_not_of('0');
-					hz = hz.substr(0, last + (last != dpos ? 1 : 0));
+					const u32 rate = u32(screen.frame_period().as_hz() * 1'000'000 + 0.5);
+					const bool valid = rate >= 1'000'000;
+					std::string hz(valid ? std::to_string(rate) : "?");
+					if (valid)
+					{
+						size_t dpos = hz.length() - 6;
+						hz.insert(dpos, ".");
+						size_t last = hz.find_last_not_of('0');
+						hz = hz.substr(0, last + (last != dpos ? 1 : 0));
+					}
 
 					const rectangle &visarea = screen.visible_area();
 					layout->add_text(
diff --git a/src/frontend/mame/ui/info.cpp b/src/frontend/mame/ui/info.cpp
index ec7d5f0242f..d7ed21065fa 100644
--- a/src/frontend/mame/ui/info.cpp
+++ b/src/frontend/mame/ui/info.cpp
@@ -464,13 +464,16 @@ std::string machine_info::game_info_string() const
 				detail = _("Vector");
 			else
 			{
-				std::string hz(std::to_string(u32(screen.frame_period().as_hz() * 1'000'000 + 0.5)));
-				size_t dpos = hz.length() - 6;
-				if (dpos == 0)
-					hz.insert(dpos++, "0");
-				hz.insert(dpos, ".");
-				size_t last = hz.find_last_not_of('0');
-				hz = hz.substr(0, last + (last != dpos ? 1 : 0));
+				const u32 rate = u32(screen.frame_period().as_hz() * 1'000'000 + 0.5);
+				const bool valid = rate >= 1'000'000;
+				std::string hz(valid ? std::to_string(rate) : "?");
+				if (valid)
+				{
+					size_t dpos = hz.length() - 6;
+					hz.insert(dpos, ".");
+					size_t last = hz.find_last_not_of('0');
+					hz = hz.substr(0, last + (last != dpos ? 1 : 0));
+				}
 
 				const rectangle &visarea = screen.visible_area();
 				detail = string_format("%d " UTF8_MULTIPLY " %d (%s) %s" UTF8_NBSP "Hz",