diff --git a/compiler/examples/test.p8 b/compiler/examples/test.p8
index 5e840063f..d3c61370f 100644
--- a/compiler/examples/test.p8
+++ b/compiler/examples/test.p8
@@ -1,5 +1,9 @@
 %option enable_floats
 
+%import c64lib
+%import mathlib
+%import prog8lib
+
 ~ main {
 
 sub start() -> () {
@@ -21,4 +25,8 @@ sub start() -> () {
     yy = (22.0/v)/11.0
 
 }
+
+sub printIt(length: XY, control: A) -> (A) {
+    return 42  ; length / control
+}
 }
diff --git a/compiler/src/prog8/ast/AstIdentifiersChecker.kt b/compiler/src/prog8/ast/AstIdentifiersChecker.kt
index 84177543e..e5ad0bfb8 100644
--- a/compiler/src/prog8/ast/AstIdentifiersChecker.kt
+++ b/compiler/src/prog8/ast/AstIdentifiersChecker.kt
@@ -65,6 +65,9 @@ class AstIdentifiersChecker : IAstProcessor {
             // the builtin functions can't be redefined
             checkResult.add(NameError("builtin function cannot be redefined", subroutine.position))
         } else {
+            if(subroutine.parameters.any { BuiltinFunctionNames.contains(it.name) })
+                checkResult.add(NameError("builtin function name cannot be used as parameter", subroutine.position))
+
             val scopedName = subroutine.scopedname
             val existing = symbols[scopedName]
             if (existing != null) {
diff --git a/compiler/src/prog8/compiler/Compiler.kt b/compiler/src/prog8/compiler/Compiler.kt
index 0bdca21de..6b295d578 100644
--- a/compiler/src/prog8/compiler/Compiler.kt
+++ b/compiler/src/prog8/compiler/Compiler.kt
@@ -103,12 +103,11 @@ class Compiler(private val options: CompilationOptions) {
         // create the pool of all variables used in all blocks and scopes
         val varGather = VarGatherer(intermediate)
         varGather.process(module)
-        println("Number of allocated variables and constants: ${intermediate.numVariables}")
+        println(" ${intermediate.numVariables} allocated variables and constants")
 
         val translator = StatementTranslator(intermediate, namespace)
         translator.process(module)
-        println("Number of source statements: ${translator.stmtUniqueSequenceNr}")
-        println("Number of vm instructions: ${intermediate.numInstructions}")
+        println(" ${translator.stmtUniqueSequenceNr} source statements,  ${intermediate.numInstructions} resulting instructions")
 
         return intermediate
     }
diff --git a/compiler/src/prog8/optimizing/Extensions.kt b/compiler/src/prog8/optimizing/Extensions.kt
index 7705b768a..1d2461862 100644
--- a/compiler/src/prog8/optimizing/Extensions.kt
+++ b/compiler/src/prog8/optimizing/Extensions.kt
@@ -22,7 +22,7 @@ fun Module.constantFold(globalNamespace: INameScope) {
     }
 
     while(optimizer.errors.isEmpty() && optimizer.optimizationsDone>0) {
-        println("[${this.name}] ${optimizer.optimizationsDone} constant folds performed")
+        println("[${this.name}] Debug: ${optimizer.optimizationsDone} constant folds performed")
         optimizer.optimizationsDone = 0
         this.process(optimizer)
     }
@@ -41,7 +41,7 @@ fun Module.optimizeStatements(globalNamespace: INameScope, allScopedSymbolDefini
     this.process(optimizer)
     optimizer.removeUnusedNodes(globalNamespace.usedNames(), allScopedSymbolDefinitions)
     if(optimizer.optimizationsDone > 0)
-        println("[${this.name}] ${optimizer.optimizationsDone} statement optimizations performed")
+        println("[${this.name}] Debug: ${optimizer.optimizationsDone} statement optimizations performed")
     this.linkParents()  // re-link in final configuration
     return optimizer.optimizationsDone
 }
@@ -50,6 +50,6 @@ fun Module.simplifyExpressions(namespace: INameScope) : Int {
     val optimizer = SimplifyExpressions(namespace)
     this.process(optimizer)
     if(optimizer.optimizationsDone > 0)
-        println("[${this.name}] ${optimizer.optimizationsDone} expression optimizations performed")
+        println("[${this.name}] Debug: ${optimizer.optimizationsDone} expression optimizations performed")
     return optimizer.optimizationsDone
 }
diff --git a/docs/source/syntaxreference.rst b/docs/source/syntaxreference.rst
index 635cea7ed..8f623fe4a 100644
--- a/docs/source/syntaxreference.rst
+++ b/docs/source/syntaxreference.rst
@@ -436,7 +436,7 @@ and not specifying a code block::
 .. data:: proc_parameters
 
         comma separated list of "<parametername>:<register>" pairs specifying the input parameters.
-        You can omit the parameter names as long as the arguments "line up".
+        You can omit these parameter names in subroutine calls, as long as the arguments "line up".
 
 .. data:: proc_results
 
diff --git a/prog8lib/c64lib.p8 b/prog8lib/c64lib.p8
index 556719cef..822b74573 100644
--- a/prog8lib/c64lib.p8
+++ b/prog8lib/c64lib.p8
@@ -142,7 +142,7 @@ sub	GIVAYF		(lo: Y, hi: A) -> (?)	= $b391
 
 sub	FREADUY		(ubyte: Y) -> (?)	= $b3a2		; 8 bit unsigned Y -> float in fac1
 sub	FREADSA		(sbyte: A) -> (?)	= $bc3c		; 8 bit signed A -> float in fac1
-sub	FREADSTR	(len: A) -> (?)		= $b7b5		; str -> fac1, $22/23 must point to string, A=string length
+sub	FREADSTR	(length: A) -> (?)	= $b7b5		; str -> fac1, $22/23 must point to string, A=string length
 sub	FPRINTLN	() -> (?)		= $aabc		; print string of fac1, on one line (= with newline)
 sub	FOUT		() -> (AY, X?)		= $bddd		; fac1 -> string, address returned in AY ($0100)