diff --git a/code/modules/reagents/chemistry/machinery/chem_heater.dm b/code/modules/reagents/chemistry/machinery/chem_heater.dm
index c31c099c255..a81b189f426 100644
--- a/code/modules/reagents/chemistry/machinery/chem_heater.dm
+++ b/code/modules/reagents/chemistry/machinery/chem_heater.dm
@@ -332,7 +332,7 @@
 				return FALSE
 
 			dispense_volume = target
-			return FALSE
+			return TRUE
 
 /**
  * Injects either acid/base buffer into the beaker
diff --git a/code/modules/reagents/chemistry/machinery/chem_synthesizer.dm b/code/modules/reagents/chemistry/machinery/chem_synthesizer.dm
index 6177baa269a..686196b73ff 100644
--- a/code/modules/reagents/chemistry/machinery/chem_synthesizer.dm
+++ b/code/modules/reagents/chemistry/machinery/chem_synthesizer.dm
@@ -45,16 +45,28 @@
 			return TRUE
 
 		if("amount")
-			var/input = text2num(params["amount"])
-			if(input)
-				amount = input
-			return FALSE
+			var/input = params["amount"]
+			if(isnull(input))
+				return FALSE
+
+			input = text2num(input)
+			if(isnull(input))
+				return FALSE
+
+			amount = input
+			return TRUE
 
 		if("purity")
-			var/input = text2num(params["amount"])
-			if(input)
-				purity = input
-			return FALSE
+			var/input = params["amount"]
+			if(isnull(input))
+				return FALSE
+
+			input = text2num(input)
+			if(isnull(input))
+				return FALSE
+
+			purity = input
+			return TRUE
 
 	update_appearance()