diff --git a/BizHawk.MultiClient/tools/Watch/NewRamSearch.Designer.cs b/BizHawk.MultiClient/tools/Watch/NewRamSearch.Designer.cs
index 209cfab5c3..2197d0e24a 100644
--- a/BizHawk.MultiClient/tools/Watch/NewRamSearch.Designer.cs
+++ b/BizHawk.MultiClient/tools/Watch/NewRamSearch.Designer.cs
@@ -77,7 +77,7 @@
 			this.toolStripSeparator1 = new System.Windows.Forms.ToolStripSeparator();
 			this.BigEndianMenuItem = new System.Windows.Forms.ToolStripMenuItem();
 			this.DefinePreviousValueSubMenu = new System.Windows.Forms.ToolStripMenuItem();
-			this.previousFrameToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
+			this.PreviousFrameMenuItem = new System.Windows.Forms.ToolStripMenuItem();
 			this.Previous_LastSearchMenuItem = new System.Windows.Forms.ToolStripMenuItem();
 			this.Previous_LastChangeMenuItem = new System.Windows.Forms.ToolStripMenuItem();
 			this.Previous_OriginalMenuItem = new System.Windows.Forms.ToolStripMenuItem();
@@ -100,7 +100,7 @@
 			this.definePreviousValueToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
 			this.sinceLastSearchToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
 			this.originalValueToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
-			this.Previous_LastFrameMenuItem = new System.Windows.Forms.ToolStripMenuItem();
+			this.Previous_LastFrameMenuItemOld = new System.Windows.Forms.ToolStripMenuItem();
 			this.sinceLastChangeToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
 			this.fastModeToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
 			this.previewModeToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
@@ -503,7 +503,7 @@
 			// DefinePreviousValueSubMenu
 			// 
 			this.DefinePreviousValueSubMenu.DropDownItems.AddRange(new System.Windows.Forms.ToolStripItem[] {
-            this.previousFrameToolStripMenuItem,
+            this.PreviousFrameMenuItem,
             this.Previous_LastSearchMenuItem,
             this.Previous_LastChangeMenuItem,
             this.Previous_OriginalMenuItem});
@@ -514,10 +514,10 @@
 			// 
 			// previousFrameToolStripMenuItem
 			// 
-			this.previousFrameToolStripMenuItem.Name = "previousFrameToolStripMenuItem";
-			this.previousFrameToolStripMenuItem.Size = new System.Drawing.Size(155, 22);
-			this.previousFrameToolStripMenuItem.Text = "&Previous Frame";
-			this.previousFrameToolStripMenuItem.Click += new System.EventHandler(this.Previous_LastFrameMenuItem_Click);
+			this.PreviousFrameMenuItem.Name = "previousFrameToolStripMenuItem";
+			this.PreviousFrameMenuItem.Size = new System.Drawing.Size(155, 22);
+			this.PreviousFrameMenuItem.Text = "&Previous Frame";
+			this.PreviousFrameMenuItem.Click += new System.EventHandler(this.Previous_LastFrameMenuItem_Click);
 			// 
 			// Previous_LastSearchMenuItem
 			// 
@@ -695,7 +695,7 @@
 			this.definePreviousValueToolStripMenuItem.DropDownItems.AddRange(new System.Windows.Forms.ToolStripItem[] {
             this.sinceLastSearchToolStripMenuItem,
             this.originalValueToolStripMenuItem,
-            this.Previous_LastFrameMenuItem,
+            this.Previous_LastFrameMenuItemOld,
             this.sinceLastChangeToolStripMenuItem});
 			this.definePreviousValueToolStripMenuItem.Enabled = false;
 			this.definePreviousValueToolStripMenuItem.Name = "definePreviousValueToolStripMenuItem";
@@ -718,10 +718,10 @@
 			// 
 			// Previous_LastFrameMenuItem
 			// 
-			this.Previous_LastFrameMenuItem.Enabled = false;
-			this.Previous_LastFrameMenuItem.Name = "Previous_LastFrameMenuItem";
-			this.Previous_LastFrameMenuItem.Size = new System.Drawing.Size(167, 22);
-			this.Previous_LastFrameMenuItem.Text = "Since last Frame";
+			this.Previous_LastFrameMenuItemOld.Enabled = false;
+			this.Previous_LastFrameMenuItemOld.Name = "Previous_LastFrameMenuItem";
+			this.Previous_LastFrameMenuItemOld.Size = new System.Drawing.Size(167, 22);
+			this.Previous_LastFrameMenuItemOld.Text = "Since last Frame";
 			// 
 			// sinceLastChangeToolStripMenuItem
 			// 
@@ -871,7 +871,7 @@
         private System.Windows.Forms.ToolStripMenuItem pokeAddressToolStripMenuItem;
         private System.Windows.Forms.ToolStripMenuItem definePreviousValueToolStripMenuItem;
         private System.Windows.Forms.ToolStripMenuItem sinceLastSearchToolStripMenuItem;
-        private System.Windows.Forms.ToolStripMenuItem Previous_LastFrameMenuItem;
+        private System.Windows.Forms.ToolStripMenuItem Previous_LastFrameMenuItemOld;
         private System.Windows.Forms.ToolStripMenuItem previewModeToolStripMenuItem;
         private System.Windows.Forms.ToolStripMenuItem originalValueToolStripMenuItem;
 		private System.Windows.Forms.ToolStripMenuItem TruncateFromFileToolStripMenuItem;
@@ -922,7 +922,7 @@
 		private System.Windows.Forms.ToolStripMenuItem CheckMisalignedMenuItem;
 		private System.Windows.Forms.ToolStripSeparator toolStripSeparator8;
 		private System.Windows.Forms.ToolStripMenuItem DefinePreviousValueSubMenu;
-		private System.Windows.Forms.ToolStripMenuItem previousFrameToolStripMenuItem;
+		private System.Windows.Forms.ToolStripMenuItem PreviousFrameMenuItem;
 		private System.Windows.Forms.ToolStripMenuItem Previous_LastSearchMenuItem;
 		private System.Windows.Forms.ToolStripMenuItem Previous_LastChangeMenuItem;
 		private System.Windows.Forms.ToolStripMenuItem Previous_OriginalMenuItem;
diff --git a/BizHawk.MultiClient/tools/Watch/NewRamSearch.cs b/BizHawk.MultiClient/tools/Watch/NewRamSearch.cs
index 8bd8de926a..8fdbc72f6d 100644
--- a/BizHawk.MultiClient/tools/Watch/NewRamSearch.cs
+++ b/BizHawk.MultiClient/tools/Watch/NewRamSearch.cs
@@ -214,6 +214,12 @@ namespace BizHawk.MultiClient
 			Searches.SetType(type);
 		}
 
+		private void SetPreviousStype(Watch.PreviousType type)
+		{
+			Settings.PreviousType = type;
+			Searches.SetPreviousType(type);
+		}
+
 		#endregion
 
 		#region Winform Events
@@ -283,7 +289,7 @@ namespace BizHawk.MultiClient
 		{
 			Previous_LastSearchMenuItem.Checked = false;
 			Previous_LastChangeMenuItem.Checked = false;
-			Previous_LastFrameMenuItem.Checked = false;
+			PreviousFrameMenuItem.Checked = false;
 			Previous_OriginalMenuItem.Checked = false;
 
 			switch (Settings.PreviousType)
@@ -296,12 +302,23 @@ namespace BizHawk.MultiClient
 					Previous_LastChangeMenuItem.Checked = true;
 					break;
 				case Watch.PreviousType.LastFrame:
-					Previous_LastFrameMenuItem.Checked = true;
+					PreviousFrameMenuItem.Checked = true;
 					break;
 				case Watch.PreviousType.Original:
 					Previous_OriginalMenuItem.Checked = true;
 					break;
 			}
+
+			if (Settings.Mode == RamSearchEngine.Settings.SearchMode.Fast)
+			{
+				Previous_LastChangeMenuItem.Enabled = false;
+				PreviousFrameMenuItem.Enabled = false;
+			}
+			else
+			{
+				Previous_LastChangeMenuItem.Enabled = true;
+				PreviousFrameMenuItem.Enabled = true;
+			}
 		}
 
 		private void DetailedMenuItem_Click(object sender, EventArgs e)
@@ -312,6 +329,11 @@ namespace BizHawk.MultiClient
 		private void FastMenuItem_Click(object sender, EventArgs e)
 		{
 			Settings.Mode = RamSearchEngine.Settings.SearchMode.Fast;
+
+			if (Settings.PreviousType == Watch.PreviousType.LastFrame || Settings.PreviousType == Watch.PreviousType.LastChange)
+			{
+				SetPreviousStype(Watch.PreviousType.LastSearch);
+			}
 		}
 
 		private void _1ByteMenuItem_Click(object sender, EventArgs e)
@@ -336,26 +358,22 @@ namespace BizHawk.MultiClient
 
 		private void Previous_LastFrameMenuItem_Click(object sender, EventArgs e)
 		{
-			Settings.PreviousType = Watch.PreviousType.LastFrame;
-			Searches.SetPreviousType(Watch.PreviousType.LastFrame);
+			SetPreviousStype(Watch.PreviousType.LastFrame);
 		}
 
 		private void Previous_LastSearchMenuItem_Click(object sender, EventArgs e)
 		{
-			Settings.PreviousType = Watch.PreviousType.LastSearch;
-			Searches.SetPreviousType(Watch.PreviousType.LastSearch);
+			SetPreviousStype(Watch.PreviousType.LastSearch);
 		}
 
 		private void Previous_LastChangeMenuItem_Click(object sender, EventArgs e)
 		{
-			Settings.PreviousType = Watch.PreviousType.LastChange;
-			Searches.SetPreviousType(Watch.PreviousType.LastChange);
+			SetPreviousStype(Watch.PreviousType.LastChange);
 		}
 
 		private void Previous_OriginalMenuItem_Click(object sender, EventArgs e)
 		{
-			Settings.PreviousType = Watch.PreviousType.Original;
-			Searches.SetPreviousType(Watch.PreviousType.Original);
+			SetPreviousStype(Watch.PreviousType.Original);
 		}
 
 		private void BigEndianMenuItem_Click(object sender, EventArgs e)
diff --git a/BizHawk.MultiClient/tools/Watch/RamSearchEngine.cs b/BizHawk.MultiClient/tools/Watch/RamSearchEngine.cs
index 2910d4e20f..ea74d9ae5b 100644
--- a/BizHawk.MultiClient/tools/Watch/RamSearchEngine.cs
+++ b/BizHawk.MultiClient/tools/Watch/RamSearchEngine.cs
@@ -160,6 +160,14 @@ namespace BizHawk.MultiClient
 
 		public void SetPreviousType(Watch.PreviousType type)
 		{
+			if (_settings.Mode == Settings.SearchMode.Fast)
+			{
+				if (type == Watch.PreviousType.LastFrame || type == Watch.PreviousType.LastChange)
+				{
+					throw new InvalidOperationException();
+				}
+			}
+			
 			_settings.PreviousType = type;
 		}