diff --git a/parser/parser.cpp b/parser/parser.cpp
index ef15fd48..9443a37c 100644
--- a/parser/parser.cpp
+++ b/parser/parser.cpp
@@ -31,15 +31,14 @@ namespace parser {
 
 // strings
 struct unicode : list< seq< one< 'u' >, rep< 4, must< xdigit > > >, one< '\\' > > {};
-struct escaped_char : one< '"', '\'', '\\', '/', 'b', 'f', 'n', 'r', 't' > {};
+struct escaped_char : one< '"', '\'', '\\', '/', 'b', 'f', 'n', 'r', 't', '0' > {};
 struct escaped : sor< escaped_char, unicode > {};
 struct unescaped : utf8::range< 0x20, 0x10FFFF > {};
-struct char_ : if_then_else< one< '\\' >, must< escaped >, unescaped > {};
-
-struct dq_string_content : until< at< one< '"' > >, must< char_ > > {};
+struct chars : if_then_else< one< '\\' >, must< escaped >, unescaped > {};
+struct dq_string_content : until< at< one< '"' > >, must< chars > > {};
 struct dq_string : seq< one< '"' >, must< dq_string_content >, any > {};
 
-struct sq_string_content : until< at< one< '\'' > >, must< char_ > > {};
+struct sq_string_content : until< at< one< '\'' > >, must< chars > > {};
 struct sq_string : seq< one< '\'' >, must< sq_string_content >, any > {};
 
 // numbers
diff --git a/parser/test.cpp b/parser/test.cpp
index 23494306..9655ee05 100644
--- a/parser/test.cpp
+++ b/parser/test.cpp
@@ -7,15 +7,50 @@
 #include <iostream>
 
 static std::vector<std::string> valid_queries = {
+    // true/false predicates
     "truepredicate",
     "falsepredicate",
     "TRUEPREDICATE",
     "FALSEPREDICATE",
-    "truepredicate && truepredicate"
+
+    // characters/strings
+    "\"\" = ''",
+    "'azAZ09/ :()[]{}<>,.^@-+=*&~`' = '\\\" \\' \\\\ \\/ \\b \\f \\n \\r \\t \\0'",
+    "\"azAZ09/\" = \"\\\" \\' \\\\ \\/ \\b \\f \\n \\r \\t \\0\"",
+    "'\\uffFf' = '\\u0020'",
+    "'\\u01111' = 'asdf\\u0111asdf'",
+
+    // numbers, bools, keypaths
+    "-1 = 12",
+    "0 = 001",
+    "0x0 = -0X398235fcAb",
+    "10. = -.034",
+    "10.0 = 5.034",
+    "true = false",
+    "_ = a",
+    "_a = _.aZ",
+    "a09._br.z = __-__.Z-9",
 };
 
 static std::vector<std::string> invalid_queries = {
     "predicate",
+    "'\\a' = ''",        // invalid escape
+
+    // invalid unicode
+    "'\\u0' = ''",
+
+    // invalid strings
+    "\"' = ''",
+    "\" = ''",
+    "' = ''",
+
+    // invalid numbers, bools, keypaths
+    "03a = 1",
+    "1..0 = 1",
+    "1.0. = 1",
+    "0x = 1",
+    "truey = false",
+
     "truepredicate &&",
     "truepredicate & truepredicate",
 };