diff --git a/include/weaseljson.h b/include/weaseljson.h
index 4a42681..aa0ec52 100644
--- a/include/weaseljson.h
+++ b/include/weaseljson.h
@@ -38,6 +38,8 @@ enum WeaselJsonStatus {
   WeaselJson_REJECT,
   /** json is too deeply nested */
   WeaselJson_OVERFLOW,
+  /** Tried to call parse on a null parser */
+  WeaselJson_NULL,
 };
 
 typedef struct WeaselJsonParser WeaselJsonParser;
@@ -65,7 +67,7 @@ void WeaselJsonParser_destroy(WeaselJsonParser *parser);
 /** Incrementally parse `len` more bytes starting at `buf`. `buf` may be
  * modified. Call with `len` 0 to indicate end of data. `buf` may be null if
  * `len` is 0. `len` must not be negative; a negative length is treated as a
- * rejected input. */
+ * rejected input. Returns WeaselJson_NULL if parser is null */
 WeaselJsonStatus WeaselJsonParser_parse(WeaselJsonParser *parser, char *buf,
                                         int len);
 
diff --git a/src/lib.cpp b/src/lib.cpp
index 715f2c6..b805e01 100644
--- a/src/lib.cpp
+++ b/src/lib.cpp
@@ -46,6 +46,9 @@ WeaselJsonParser_destroy(WeaselJsonParser *parser) {
 
 __attribute__((visibility("default"))) WeaselJsonStatus
 WeaselJsonParser_parse(WeaselJsonParser *parser, char *buf, int len) {
+  if (parser == nullptr) [[unlikely]] {
+    return WeaselJson_NULL;
+  }
   return ((Parser3 *)parser)->parse(buf, len);
 }
 }
diff --git a/src/test.cpp b/src/test.cpp
index 6fef3a7..10cb1fb 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -330,6 +330,10 @@ TEST_CASE("parse rejects negative length") {
   WeaselJsonParser_destroy(parser);
 }
 
+TEST_CASE("Calling parse with nullptr doesn't crash") {
+  REQUIRE(WeaselJsonParser_parse(nullptr, nullptr, 0) == WeaselJson_NULL);
+}
+
 TEST_CASE("streaming") { testStreaming(json); }
 
 TEST_CASE("reset clears inKey and transient state") {
diff --git a/src/validate.cpp b/src/validate.cpp
index abbd2fa..9566056 100644
--- a/src/validate.cpp
+++ b/src/validate.cpp
@@ -33,6 +33,9 @@ int main(int argc, char **argv) {
     case WeaselJson_REJECT:
     case WeaselJson_OVERFLOW:
       return 1;
+    case WeaselJson_NULL:
+      fprintf(stderr, "parse called with a null parser\n");
+      return 1;
     }
     if (l == 0) {
       return 1;
diff --git a/weaseljson.py b/weaseljson.py
index 7063c98..777d8fe 100644
--- a/weaseljson.py
+++ b/weaseljson.py
@@ -30,6 +30,7 @@ class WeaselJsonStatus(enum.Enum):
     AGAIN = 1
     REJECT = 2
     OVERFLOW = 3
+    NULL = 4
 
 
 class WeaselJsonCallbacksBase: