diff --git a/src/cc65/expr.c b/src/cc65/expr.c
index 44b0d17e8..048819d50 100644
--- a/src/cc65/expr.c
+++ b/src/cc65/expr.c
@@ -3658,7 +3658,7 @@ static int hieAnd (ExprDesc* Expr, unsigned* TrueLab, int* TrueLabAllocated)
                 */
                 DoDeferred (SQP_KEEP_NONE, Expr);
 
-                if (Expr->IVal == 0 && !ED_IsAddrExpr (Expr)) {
+                if (ED_IsConstFalse (Expr)) {
                     /* Skip remaining */
                     Flags |= E_EVAL_UNEVAL;
                 }
@@ -3713,7 +3713,7 @@ static int hieAnd (ExprDesc* Expr, unsigned* TrueLab, int* TrueLabAllocated)
                     */
                     DoDeferred (SQP_KEEP_NONE, &Expr2);
 
-                    if (Expr2.IVal == 0 && !ED_IsAddrExpr (&Expr2)) {
+                    if (ED_IsConstFalse (&Expr2)) {
                         /* Skip remaining */
                         Flags |= E_EVAL_UNEVAL;
                         /* The value of the expression will be false */
@@ -3826,7 +3826,7 @@ static void hieOr (ExprDesc *Expr)
                 */
                 DoDeferred (SQP_KEEP_NONE, Expr);
 
-                if (Expr->IVal != 0 || ED_IsAddrExpr (Expr)) {
+                if (ED_IsConstTrue (Expr)) {
                     /* Skip remaining */
                     Flags |= E_EVAL_UNEVAL;
                 }
@@ -3878,7 +3878,7 @@ static void hieOr (ExprDesc *Expr)
                     */
                     DoDeferred (SQP_KEEP_NONE, &Expr2);
 
-                    if (Expr2.IVal != 0 || ED_IsAddrExpr (&Expr2)) {
+                    if (ED_IsConstTrue (&Expr2)) {
                         /* Skip remaining */
                         Flags |= E_EVAL_UNEVAL;
                         /* The result is always true */
@@ -3945,6 +3945,7 @@ static void hieQuest (ExprDesc* Expr)
     /* Check if it's a ternary expression */
     if (CurTok.Tok == TOK_QUEST) {
 
+        /* The constant condition must be compile-time known as well */
         int ConstantCond = ED_IsConstBool (Expr);
         unsigned Flags   = Expr->Flags & E_MASK_KEEP_RESULT;
 
@@ -3955,9 +3956,13 @@ static void hieQuest (ExprDesc* Expr)
 
         NextToken ();
 
-        /* Convert non-integer constant boolean */
-        if (ED_IsAddrExpr (Expr)) {
+        /* Convert non-integer constant to boolean constant, so that we may just
+        ** check it in the same way.
+        */
+        if (ED_IsConstTrue (Expr)) {
             ED_MakeConstBool (Expr, 1);
+        } else if (ED_IsConstFalse (Expr)) {
+            ED_MakeConstBool (Expr, 0);
         }
 
         if (!ConstantCond) {
diff --git a/src/cc65/exprdesc.c b/src/cc65/exprdesc.c
index aa98e1531..d1113d9a5 100644
--- a/src/cc65/exprdesc.c
+++ b/src/cc65/exprdesc.c
@@ -397,6 +397,30 @@ int ED_IsConstBool (const ExprDesc* Expr)
 
 
 
+int ED_IsConstTrue (const ExprDesc* Expr)
+/* Return true if the constant expression can be evaluated as boolean true at
+** compile time.
+*/
+{
+    /* Non-zero arithmetics and objects addresses are boolean true */
+    return (ED_IsConstAbsInt (Expr) && Expr->IVal != 0) ||
+           (ED_IsAddrExpr (Expr));
+}
+
+
+
+int ED_IsConstFalse (const ExprDesc* Expr)
+/* Return true if the constant expression can be evaluated as boolean false at
+** compile time.
+*/
+{
+    /* Zero arithmetics and null pointers are boolean false */
+    return (ED_IsConstAbsInt (Expr) && Expr->IVal == 0) ||
+           ED_IsNullPtr (Expr);
+}
+
+
+
 int ED_IsConst (const ExprDesc* Expr)
 /* Return true if the expression denotes a constant of some sort. This can be a
 ** numeric constant, the address of a global variable (maybe with offset) or
@@ -449,7 +473,7 @@ int ED_IsNullPtr (const ExprDesc* Expr)
 
 
 int ED_IsBool (const ExprDesc* Expr)
-/* Return true of the expression can be treated as a boolean, that is, it can
+/* Return true if the expression can be treated as a boolean, that is, it can
 ** be an operand to a compare operation.
 */
 {
diff --git a/src/cc65/exprdesc.h b/src/cc65/exprdesc.h
index 844af1566..a4f5eb848 100644
--- a/src/cc65/exprdesc.h
+++ b/src/cc65/exprdesc.h
@@ -643,6 +643,16 @@ int ED_IsConstAbsInt (const ExprDesc* Expr);
 int ED_IsConstBool (const ExprDesc* Expr);
 /* Return true if the expression can be constantly evaluated as a boolean. */
 
+int ED_IsConstTrue (const ExprDesc* Expr);
+/* Return true if the constant expression can be evaluated as boolean true at
+** compile time.
+*/
+
+int ED_IsConstFalse (const ExprDesc* Expr);
+/* Return true if the constant expression can be evaluated as boolean false at
+** compile time.
+*/
+
 int ED_IsConst (const ExprDesc* Expr);
 /* Return true if the expression denotes a constant of some sort. This can be a
 ** numeric constant, the address of a global variable (maybe with offset) or
@@ -668,7 +678,7 @@ int ED_IsNullPtr (const ExprDesc* Expr);
 /* Return true if the given expression is a NULL pointer constant */
 
 int ED_IsBool (const ExprDesc* Expr);
-/* Return true of the expression can be treated as a boolean, that is, it can
+/* Return true if the expression can be treated as a boolean, that is, it can
 ** be an operand to a compare operation with 0/NULL.
 */