diff --git a/fx92/ast.py b/fx92/ast.py
index 2db8b98..ab8944c 100644
--- a/fx92/ast.py
+++ b/fx92/ast.py
@@ -42,7 +42,7 @@ class N(enum.IntEnum):
 
     # Flow control
     REPEAT  = enum.auto()
-    WHILE   = enum.auto()
+    UNTIL   = enum.auto()
     IF      = enum.auto()
 
     # Expressions
diff --git a/fx92/interpreter.py b/fx92/interpreter.py
index 4a7c215..391e7d7 100644
--- a/fx92/interpreter.py
+++ b/fx92/interpreter.py
@@ -132,8 +132,8 @@ class Context:
             for i in range(count):
                 self.run(n.args[1])
 
-        elif n.type == N.WHILE:
-            while self.run(n.args[0]):
+        elif n.type == N.UNTIL:
+            while not self.run(n.args[0]):
                 self.run(n.args[1])
 
         elif n.type == N.IF:
diff --git a/fx92/lexer.py b/fx92/lexer.py
index 02fabff..9dfef64 100644
--- a/fx92/lexer.py
+++ b/fx92/lexer.py
@@ -33,8 +33,8 @@ class T(enum.IntEnum):
     # Flow control
     REPEAT     = 0xF911
     REPEAT_END = 0xF912
-    WHILE      = 0xF913
-    WHILE_END  = 0xF914
+    UNTIL      = 0xF913
+    UNTIL_END  = 0xF914
     IF         = 0xF915
     IF_END     = 0xF916
     IFELSE     = 0xF917
@@ -331,7 +331,7 @@ class TextLexer(LexerBase):
 
     RE_STMTS = re.compile(
         r"NOP|FORWARD|ROTATE|ORIENT|GOTO|PENDOWN|PENUP|SETVAR|INPUT|MESSAGE|"
-        r"PRINT|STYLE|WAIT|REPEAT_END|REPEAT|WHILE_END|WHILE|IF_END|ELSE|"
+        r"PRINT|STYLE|WAIT|REPEAT_END|REPEAT|UNTIL_END|UNTIL|IF_END|ELSE|"
         r"IFELSE_END|IFELSE|IF",
         re.IGNORECASE)
     RE_CONST = re.compile(
diff --git a/fx92/parser.py b/fx92/parser.py
index a678ee1..e72a5ba 100644
--- a/fx92/parser.py
+++ b/fx92/parser.py
@@ -20,7 +20,7 @@ class Parser:
                PENDOWN | PENUP | SETVAR arg argvar | INPUT argvar |
                MESSAGE arg | PRINT arg | STYLE style | WAIT arg |
                REPEAT arg program REPEAT_END |
-               WHILE cond PARAM program WHILE_END |
+               UNTIL cond PARAM program UNTIL_END |
                IF cond PARAM program IF_END |
                IFELSE cond PARAM program ELSE program IFELSE_END
     arg     -> expr PARAM
@@ -112,7 +112,7 @@ class Parser:
         valid = [
             T.FORWARD, T.ROTATE, T.ORIENT,  T.GOTO,  T.PENDOWN, T.PENUP,
             T.SETVAR,  T.INPUT,  T.MESSAGE, T.PRINT, T.STYLE,   T.WAIT,
-            T.REPEAT,  T.WHILE,  T.IF,      T.IFELSE,
+            T.REPEAT,  T.UNTIL,  T.IF,      T.IFELSE,
         ]
         op = self.expect(*valid, optional=optional)
 
@@ -155,14 +155,14 @@ class Parser:
             self.expect(T.EOL, optional=True)
             return Node(N.REPEAT, arg, prg)
 
-        if op.type == T.WHILE:
+        if op.type == T.UNTIL:
             cond = self.cond()
             self.expect(T.PARAM)
             self.expect(T.EOL, optional=True)
             prg = self.program()
-            self.expect(T.WHILE_END)
+            self.expect(T.UNTIL_END)
             self.expect(T.EOL, optional=True)
-            return Node(N.WHILE, cond, prg)
+            return Node(N.UNTIL, cond, prg)
 
         if op.type == T.IF:
             cond = self.cond()
diff --git a/tests/line-positive.txt b/tests/line-positive.txt
index 3835185..ea75460 100644
--- a/tests/line-positive.txt
+++ b/tests/line-positive.txt
@@ -1,12 +1,12 @@
 setvar 0, A
-while A <= 5
+until A=6
   setvar 0, B
-  while B <= 12
+  until B=13
     penup
     goto 14*B-90, 7*A-20
     pendown
     goto 15*B-90, 8*A-20
     setvar B+1, B
-  while_end
+  until_end
   setvar A+1, A
-while_end
+until_end