diff --git a/packages/queryLanguage/src/tokens.ts b/packages/queryLanguage/src/tokens.ts
index 1bb69f531..043462200 100644
--- a/packages/queryLanguage/src/tokens.ts
+++ b/packages/queryLanguage/src/tokens.ts
@@ -673,27 +673,12 @@ export const negateToken = new ExternalTokenizer((input, stack) => {
         }
     }
 
-    // Check if followed by a prefix keyword (by checking for keyword followed by colon)
-    let foundColon = false;
-    let peekOffset = offset;
-    
-    while (true) {
-        const ch = input.peek(peekOffset);
-        if (ch === EOF) break;
-        
-        if (ch === COLON) {
-            foundColon = true;
-            break;
-        }
-        // Hit a delimiter (whitespace, paren, or quote) - not a prefix keyword
-        if (isWhitespace(ch) || ch === OPEN_PAREN || ch === CLOSE_PAREN || ch === QUOTE) {
-            break;
-        }
-        peekOffset++;
-    }
-    
-    if (foundColon) {
-        // It's a prefix keyword, accept as negate
+    // Only accept as negate when the dash is immediately followed by a known
+    // prefix keyword (e.g. `-file:`). A bare word that merely contains a colon
+    // (e.g. `-foo:bar`, `-http://x`) is not a prefix and must be left for
+    // wordToken; otherwise the grammar has no PrefixExpr to follow the negate
+    // token and the (strict) parser throws a SyntaxError.
+    if (startsWithPrefixAt(input, offset)) {
         input.advance();
         input.acceptToken(negate);
         return;
diff --git a/packages/queryLanguage/test/negation.txt b/packages/queryLanguage/test/negation.txt
index 105c96347..b1d8755aa 100644
--- a/packages/queryLanguage/test/negation.txt
+++ b/packages/queryLanguage/test/negation.txt
@@ -277,3 +277,27 @@ chat lang:TypeScript -file:(test|spec)
 ==>
 
 Program(AndExpr(Term,PrefixExpr(LangExpr),NegateExpr(PrefixExpr(FileExpr))))
+
+# Dash term with non-prefix colon word (e.g. a URL) stays a single Term
+
+-http://example.com
+
+==>
+
+Program(Term)
+
+# Dash term with unknown colon key stays a single Term
+
+-time:12
+
+==>
+
+Program(Term)
+
+# Prefix combined with a negated non-prefix colon word
+
+repo:x -foo:bar
+
+==>
+
+Program(AndExpr(PrefixExpr(RepoExpr),Term))