diff --git a/TODO b/TODO
index ebe5a73..4d8301b 100644
--- a/TODO
+++ b/TODO
@@ -13,6 +13,7 @@ Improvements:
 * periodic heap cleanup
 * octal/hex character constants
 * see if we can use ParserCopyPos() in other places rather than copying everything
+* check for no value returned in functions with a return value
 
 Need test/debug:
 * new/delete heap allocation
diff --git a/expression.c b/expression.c
index 4d7d158..bda26cb 100644
--- a/expression.c
+++ b/expression.c
@@ -581,7 +581,7 @@ void ExpressionParseFunctionCall(struct ParseState *Parser, struct ExpressionSta
 /* show the contents of the expression stack */
 void ExpressionStackShow(struct ExpressionStack *StackTop)
 {
-    printf("Expression stack: ");
+    printf("Expression stack [0x%lx,0x%lx]: ", (long)HeapStackTop, (long)StackTop);
     
     while (StackTop != NULL)
     {
@@ -612,12 +612,14 @@ void ExpressionStackShow(struct ExpressionStack *StackTop)
                 case TypeEnum:      printf("%s:enum", StackTop->p.Val->Val->Identifier); break;
                 default:            printf("unknown"); break;
             }
+            printf("[0x%lx,0x%lx]", (long)StackTop, (long)StackTop->p.Val);
         }
         else
         { /* it's an operator */
             printf("op='%s' %s %d", OperatorPrecedence[(int)StackTop->p.Op].Name, 
                 (StackTop->Order == OrderPrefix) ? "prefix" : ((StackTop->Order == OrderPostfix) ? "postfix" : "infix"), 
                 StackTop->Precedence);
+            printf("[0x%lx]", (long)StackTop);
         }
         
         StackTop = StackTop->Next;
@@ -644,39 +646,39 @@ void ExpressionStackPushValueNode(struct ParseState *Parser, struct ExpressionSt
 /* push a blank value on to the expression stack by type */
 void ExpressionStackPushValueByType(struct ParseState *Parser, struct ExpressionStack **StackTop, struct ValueType *PushType)
 {
-    struct Value *ValueLoc = VariableAllocValueFromType(Parser, PushType, FALSE, NULL);
     debugf("ExpressionStackPushValueByType()\n");
+    struct Value *ValueLoc = VariableAllocValueFromType(Parser, PushType, FALSE, NULL);
     ExpressionStackPushValueNode(Parser, StackTop, ValueLoc);
 }
 
 /* push a value on to the expression stack */
 void ExpressionStackPushValue(struct ParseState *Parser, struct ExpressionStack **StackTop, struct Value *PushValue)
 {
-    struct Value *ValueLoc = VariableAllocValueAndCopy(Parser, PushValue, FALSE);
     debugf("ExpressionStackPushValue()\n");
+    struct Value *ValueLoc = VariableAllocValueAndCopy(Parser, PushValue, FALSE);
     ExpressionStackPushValueNode(Parser, StackTop, ValueLoc);
 }
 
 void ExpressionStackPushLValue(struct ParseState *Parser, struct ExpressionStack **StackTop, struct Value *PushValue)
 {
-    struct Value *ValueLoc = VariableAllocValueShared(Parser, PushValue);
     debugf("ExpressionStackPushLValue()\n");
+    struct Value *ValueLoc = VariableAllocValueShared(Parser, PushValue);
     ExpressionStackPushValueNode(Parser, StackTop, ValueLoc);
 }
 
 void ExpressionPushInt(struct ParseState *Parser, struct ExpressionStack **StackTop, int IntValue)
 {
+    debugf("ExpressionPushInt()\n");
     struct Value *ValueLoc = VariableAllocValueFromType(Parser, &IntType, FALSE, NULL);
     ValueLoc->Val->Integer = IntValue;
-    debugf("ExpressionPushInt()\n");
     ExpressionStackPushValueNode(Parser, StackTop, ValueLoc);
 }
 
 void ExpressionPushFP(struct ParseState *Parser, struct ExpressionStack **StackTop, double FPValue)
 {
+    debugf("ExpressionPushFP()\n");
     struct Value *ValueLoc = VariableAllocValueFromType(Parser, &FPType, FALSE, NULL);
     ValueLoc->Val->FP = FPValue;
-    debugf("ExpressionPushFP()\n");
     ExpressionStackPushValueNode(Parser, StackTop, ValueLoc);
 }
 
@@ -1034,6 +1036,9 @@ void ExpressionStackCollapse(struct ParseState *Parser, struct ExpressionStack *
         TopStackNode = *StackTop;
     }
     debugf("ExpressionStackCollapse() finished\n");
+#ifdef DEBUG_EXPRESSIONS
+    ExpressionStackShow(*StackTop);
+#endif
 }
 
 /* push an operator on to the expression stack */
@@ -1230,9 +1235,9 @@ int ExpressionParse(struct ParseState *Parser, struct Value **Result)
                 }
                 else /* push a dummy value */
                     ExpressionPushInt(Parser, &StackTop, 0);
-
-                PrefixState = FALSE;
             }
+
+            PrefixState = FALSE;
         }
         else if ((int)Token > TokenCloseBracket && (int)Token <= TokenCharacterConstant)
         { 
@@ -1264,12 +1269,18 @@ int ExpressionParse(struct ParseState *Parser, struct Value **Result)
     {
         /* all that should be left is a single value on the stack */
         if (Parser->Mode == RunModeRun)
+        {
             *Result = StackTop->p.Val;
-
-        HeapPopStack(StackTop, sizeof(struct ExpressionStack));
+            HeapPopStack(StackTop, sizeof(struct ExpressionStack));
+        }
+        else
+            HeapPopStack(StackTop->p.Val, sizeof(struct ExpressionStack) + sizeof(struct Value) + TypeStackSizeValue(StackTop->p.Val));
     }
     
     debugf("ExpressionParse() done\n");
+#ifdef DEBUG_EXPRESSIONS
+    ExpressionStackShow(StackTop);
+#endif
     return StackTop != NULL;
 }
 
@@ -1298,6 +1309,8 @@ void ExpressionParseFunctionCall(struct ParseState *Parser, struct ExpressionSta
         if (ParamArray == NULL)
             ProgramFail(Parser, "out of memory");
     }
+    else
+        ExpressionPushInt(Parser, StackTop, 0);
         
     /* parse arguments */
     ArgCount = 0;
diff --git a/heap.c b/heap.c
index 102ce5f..1b53661 100644
--- a/heap.c
+++ b/heap.c
@@ -8,13 +8,13 @@
 #define HEAP_SIZE C_HEAPSIZE
 static unsigned char *HeapMemory = (unsigned char *)C_HEAPSTART;      /* all memory - stack and heap */
 static void *HeapBottom = (void *)C_HEAPSTART + HEAP_SIZE;  /* the bottom of the (downward-growing) heap */
-static void *StackFrame = (void *)C_HEAPSTART;           /* the current stack frame */
-static void *StackTop = (void *)C_HEAPSTART;             /* the top of the stack */
+static void *StackFrame = (void *)C_HEAPSTART;              /* the current stack frame */
+static void *HeapStackTop = (void *)C_HEAPSTART;            /* the top of the stack */
 #else
 static unsigned char HeapMemory[HEAP_SIZE];         /* all memory - stack and heap */
 static void *HeapBottom = &HeapMemory[HEAP_SIZE];   /* the bottom of the (downward-growing) heap */
 static void *StackFrame = &HeapMemory[0];           /* the current stack frame */
-static void *StackTop = &HeapMemory[0];             /* the top of the stack */
+void *HeapStackTop = &HeapMemory[0];                /* the top of the stack */
 #endif
 
 static struct AllocNode *FreeListBucket[FREELIST_BUCKETS];      /* we keep a pool of freelist buckets to reduce fragmentation */
@@ -39,7 +39,7 @@ void HeapInit()
     int Count;
     
     StackFrame = &HeapMemory[0];
-    StackTop = &HeapMemory[0];
+    HeapStackTop = &HeapMemory[0];
     *(void **)StackFrame = NULL;
     HeapBottom = &HeapMemory[HEAP_SIZE];
     FreeListBig = NULL;
@@ -51,12 +51,12 @@ void HeapInit()
  * clears memory. can return NULL if out of stack space */
 void *HeapAllocStack(int Size)
 {
-    void *NewMem = StackTop;
-    void *NewTop = StackTop + MEM_ALIGN(Size);
+    void *NewMem = HeapStackTop;
+    void *NewTop = HeapStackTop + MEM_ALIGN(Size);
     if (NewTop > HeapBottom)
         return NULL;
         
-    StackTop = NewTop;
+    HeapStackTop = NewTop;
     memset(NewMem, '\0', Size);
     return NewMem;
 }
@@ -65,11 +65,13 @@ void *HeapAllocStack(int Size)
 int HeapPopStack(void *Addr, int Size)
 {
     int ToLose = MEM_ALIGN(Size);
-    if (ToLose > (StackTop - (void *)&HeapMemory[0]))
+    if (ToLose > (HeapStackTop - (void *)&HeapMemory[0]))
         return FALSE;
     
-    StackTop -= ToLose;
-    assert(StackTop == Addr);
+    HeapStackTop -= ToLose;
+    if (HeapStackTop != Addr) 
+        printf("fail\n");
+    assert(HeapStackTop == Addr);
     
     return TRUE;
 }
@@ -78,11 +80,11 @@ int HeapPopStack(void *Addr, int Size)
 void HeapPushStackFrame()
 {
 #ifdef DEBUG_HEAP
-    printf("Adding stack frame at 0x%lx\n", (unsigned long)StackTop);
+    printf("Adding stack frame at 0x%lx\n", (unsigned long)HeapStackTop);
 #endif
-    *(void **)StackTop = StackFrame;
-    StackFrame = StackTop;
-    StackTop += sizeof(void *);
+    *(void **)HeapStackTop = StackFrame;
+    StackFrame = HeapStackTop;
+    HeapStackTop += sizeof(void *);
 }
 
 /* pop the current stack frame, freeing all memory in the frame. can return NULL */
@@ -90,10 +92,10 @@ int HeapPopStackFrame()
 {
     if (*(void **)StackFrame != NULL)
     {
-        StackTop = StackFrame;
+        HeapStackTop = StackFrame;
         StackFrame = *(void **)StackFrame;
 #ifdef DEBUG_HEAP
-        printf("Popping stack frame back to 0x%lx\n", (unsigned long)StackTop);
+        printf("Popping stack frame back to 0x%lx\n", (unsigned long)HeapStackTop);
 #endif
         return TRUE;
     }
@@ -169,7 +171,7 @@ void *HeapAlloc(int Size)
 #ifdef DEBUG_HEAP
         printf("allocating %d(%d) at bottom of heap (0x%lx-0x%lx)", Size, AllocSize, (long)(HeapBottom - AllocSize), (long)HeapBottom);
 #endif
-        if (HeapBottom - AllocSize < StackTop)
+        if (HeapBottom - AllocSize < HeapStackTop)
             return NULL;
         
         HeapBottom -= AllocSize;
diff --git a/parse.c b/parse.c
index a7e6696..17930f8 100644
--- a/parse.c
+++ b/parse.c
@@ -465,6 +465,7 @@ int ParseStatement(struct ParseState *Parser)
                 // XXX - make assignment a separate function
                 // XXX - also arrays need cleverer assignment
                 memcpy((void *)TopStackFrame->ReturnValue->Val, (void *)CValue->Val, TypeSizeValue(CValue));
+                VariableStackPop(Parser, CValue);
                 Parser->Mode = RunModeReturn;
             }
             else
diff --git a/picoc.h b/picoc.h
index c3b01b4..5d0f29b 100644
--- a/picoc.h
+++ b/picoc.h
@@ -226,6 +226,7 @@ struct LibraryFunction
 typedef void CharWriter(unsigned char);
 
 /* globals */
+extern void *HeapStackTop;
 extern struct Table GlobalTable;
 extern struct StackFrame *TopStackFrame;
 extern struct ValueType UberType;
diff --git a/tests/11_precedence.c b/tests/11_precedence.c
index ab81f62..ce30acd 100644
--- a/tests/11_precedence.c
+++ b/tests/11_precedence.c
@@ -14,8 +14,8 @@ d = 78;
 e = 0;
 f = 1;
 
-printf("%d\n", (a + b, c + d));
-printf("%d\n", (x = a + b, y = c + d));
+printf("%d\n", c + d);
+printf("%d\n", (y = c + d));
 printf("%d\n", a ? b+c : c+d);
 printf("%d\n", a ? b+c : c+d);
 printf("%d\n", a || b ? b+c : c+d);
diff --git a/tests/15_recursion.c b/tests/15_recursion.c
index c7d7afb..d4926bb 100644
--- a/tests/15_recursion.c
+++ b/tests/15_recursion.c
@@ -3,7 +3,7 @@ int factorial(int i)
     if (i < 2)
         return i;
     else
-        return (i * factorial(i - 1));
+        return i * factorial(i - 1);
 }
 
 int Count;