diff --git a/codeGeneration/src/prog8/compiler/target/C64Target.kt b/codeGeneration/src/prog8/compiler/target/C64Target.kt
index f16fe858f..9d30c52da 100644
--- a/codeGeneration/src/prog8/compiler/target/C64Target.kt
+++ b/codeGeneration/src/prog8/compiler/target/C64Target.kt
@@ -27,7 +27,7 @@ object C64Target: ICompilationTarget {
         if (altEncoding) Petscii.decodeScreencode(bytes, true) else Petscii.decodePetscii(bytes, true)
 
     override fun asmsubArgsEvalOrder(sub: Subroutine): List<Int> = asmsub6502ArgsEvalOrder(sub)
-    override fun asmsubArgsHaveRegisterClobberRisk(args: List<Expression>): Boolean  = asmsub6502ArgsHaveRegisterClobberRisk(args)
+    override fun asmsubArgsHaveRegisterClobberRisk(args: List<Expression>) = asmsub6502ArgsHaveRegisterClobberRisk(args)
 
     override fun memorySize(dt: DataType): Int {
         return when(dt) {
diff --git a/codeGeneration/src/prog8/compiler/target/Cx16Target.kt b/codeGeneration/src/prog8/compiler/target/Cx16Target.kt
index e75204cdb..7a634d60c 100644
--- a/codeGeneration/src/prog8/compiler/target/Cx16Target.kt
+++ b/codeGeneration/src/prog8/compiler/target/Cx16Target.kt
@@ -28,7 +28,7 @@ object Cx16Target: ICompilationTarget {
         if (altEncoding) Petscii.decodeScreencode(bytes, true) else Petscii.decodePetscii(bytes, true)
 
     override fun asmsubArgsEvalOrder(sub: Subroutine): List<Int> = asmsub6502ArgsEvalOrder(sub)
-    override fun asmsubArgsHaveRegisterClobberRisk(args: List<Expression>): Boolean  = asmsub6502ArgsHaveRegisterClobberRisk(args)
+    override fun asmsubArgsHaveRegisterClobberRisk(args: List<Expression>) = asmsub6502ArgsHaveRegisterClobberRisk(args)
 
     override fun memorySize(dt: DataType): Int {
         return when(dt) {
diff --git a/compiler/src/prog8/compiler/astprocessing/AstChecker.kt b/compiler/src/prog8/compiler/astprocessing/AstChecker.kt
index d227c7c36..bd47edd82 100644
--- a/compiler/src/prog8/compiler/astprocessing/AstChecker.kt
+++ b/compiler/src/prog8/compiler/astprocessing/AstChecker.kt
@@ -981,19 +981,31 @@ internal class AstChecker(private val program: Program,
             checkUnusedReturnValues(functionCallStatement, targetStatement, program, errors)
         }
 
-        if(functionCallStatement.target.nameInSource.last() == "sort") {
-            // sort is not supported on float arrays
-            val idref = functionCallStatement.args.singleOrNull() as? IdentifierReference
-            if(idref!=null && idref.inferType(program) istype DataType.ARRAY_F) {
-                errors.err("sorting a floating point array is not supported", functionCallStatement.args.first().position)
-            }
-        }
+        val funcName = functionCallStatement.target.nameInSource
 
-        if(functionCallStatement.target.nameInSource.last() in arrayOf("rol", "ror", "rol2", "ror2", "swap", "sort", "reverse")) {
-            // in-place modification, can't be done on literals
-            if(functionCallStatement.args.any { it !is IdentifierReference && it !is ArrayIndexedExpression && it !is DirectMemoryRead }) {
-                errors.err("invalid argument to a in-place modifying function", functionCallStatement.args.first().position)
+        if(funcName.size==1) {
+            // check some builtin function calls
+            if(funcName[0] == "sort") {
+                // sort is not supported on float arrays
+                val idref = functionCallStatement.args.singleOrNull() as? IdentifierReference
+                if(idref!=null && idref.inferType(program) istype DataType.ARRAY_F) {
+                    errors.err("sorting a floating point array is not supported", functionCallStatement.args.first().position)
+                }
             }
+            else if(funcName[0] in arrayOf("pop", "popw")) {
+                // can only pop into a variable, that has to have the correct type
+                val idref = functionCallStatement.args.singleOrNull() as? IdentifierReference
+                if(idref==null)
+                    errors.err("invalid argument to pop, must be a variable with the correct type: ${functionCallStatement.args.first()}", functionCallStatement.args.first().position)
+            }
+
+            if(funcName[0] in arrayOf("rol", "ror", "rol2", "ror2", "swap", "sort", "reverse")) {
+                // in-place modification, can't be done on literals
+                if(functionCallStatement.args.any { it !is IdentifierReference && it !is ArrayIndexedExpression && it !is DirectMemoryRead }) {
+                    errors.err("invalid argument to a in-place modifying function", functionCallStatement.args.first().position)
+                }
+            }
+
         }
 
         val error =
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 6a4d59dd8..e5b476417 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -6,7 +6,8 @@ For next compiler release (7.4)
 Use GoSub to call subroutines (statements):
     - [DONE] allow separate assigns to subroutine's parameter variables / registers
     - [DONE] turn a regular subroutine call into assignments to the parameters + GoSub (take code from gosub branch)
-    - also do this for asmsubs taking >0 parameters
+    - [DONE] also do this for asmsubs taking >0 parameters
+    - make that push(x+1) doesn't use stack evaluation, via a temp var?
 
 Optimize Function calls in expressions:
     - move args to assignments to params
diff --git a/examples/test.p8 b/examples/test.p8
index 16804ad7f..672e6d5a7 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -8,9 +8,9 @@ main {
 
         uword @shared uw
         ubyte @shared ub
+        word @shared ww
 
         push(127)
-        popw(ub)            ; TODO give type error
         pop(ub)
         txt.print_ub(ub)
         txt.nl()