diff --git a/prism/prism.c b/prism/prism.c
index a382a6b18c17b3..ec319f2cac76f8 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -1340,6 +1340,11 @@ pm_assoc_node_create(pm_parser_t *parser, pm_node_t *key, const pm_token_t *oper
         flags = key->flags & value->flags & PM_NODE_FLAG_STATIC_LITERAL;
     }
 
+    // Hash string keys should be frozen
+    if (PM_NODE_TYPE_P(key, PM_STRING_NODE)) {
+        key->flags |= PM_STRING_FLAGS_FROZEN;
+    }
+
     *node = (pm_assoc_node_t) {
         {
             .type = PM_ASSOC_NODE,
diff --git a/test/prism/snapshots/unparser/corpus/literal/literal.txt b/test/prism/snapshots/unparser/corpus/literal/literal.txt
index 21ae9f670b74ac..a26b9251963980 100644
--- a/test/prism/snapshots/unparser/corpus/literal/literal.txt
+++ b/test/prism/snapshots/unparser/corpus/literal/literal.txt
@@ -9,7 +9,7 @@
         │   │   ├── @ AssocNode (location: (1,2)-(1,21))
         │   │   │   ├── key:
         │   │   │   │   @ StringNode (location: (1,2)-(1,7))
-        │   │   │   │   ├── flags: ∅
+        │   │   │   │   ├── flags: frozen
         │   │   │   │   ├── opening_loc: (1,2)-(1,3) = "\""
         │   │   │   │   ├── content_loc: (1,3)-(1,6) = "foo"
         │   │   │   │   ├── closing_loc: (1,6)-(1,7) = "\""
@@ -39,7 +39,7 @@
         │   │   └── @ AssocNode (location: (1,23)-(1,36))
         │   │       ├── key:
         │   │       │   @ StringNode (location: (1,23)-(1,28))
-        │   │       │   ├── flags: ∅
+        │   │       │   ├── flags: frozen
         │   │       │   ├── opening_loc: (1,23)-(1,24) = "\""
         │   │       │   ├── content_loc: (1,24)-(1,27) = "bar"
         │   │       │   ├── closing_loc: (1,27)-(1,28) = "\""
@@ -59,7 +59,7 @@
         │   │   ├── @ AssocNode (location: (4,2)-(4,14))
         │   │   │   ├── key:
         │   │   │   │   @ StringNode (location: (4,2)-(4,7))
-        │   │   │   │   ├── flags: ∅
+        │   │   │   │   ├── flags: frozen
         │   │   │   │   ├── opening_loc: (4,2)-(4,3) = "\""
         │   │   │   │   ├── content_loc: (4,3)-(4,6) = "foo"
         │   │   │   │   ├── closing_loc: (4,6)-(4,7) = "\""
@@ -75,7 +75,7 @@
         │   │   └── @ AssocNode (location: (4,16)-(4,29))
         │   │       ├── key:
         │   │       │   @ StringNode (location: (4,16)-(4,21))
-        │   │       │   ├── flags: ∅
+        │   │       │   ├── flags: frozen
         │   │       │   ├── opening_loc: (4,16)-(4,17) = "\""
         │   │       │   ├── content_loc: (4,17)-(4,20) = "bar"
         │   │       │   ├── closing_loc: (4,20)-(4,21) = "\""
@@ -184,7 +184,7 @@
         │   │   ├── @ AssocNode (location: (10,2)-(10,21))
         │   │   │   ├── key:
         │   │   │   │   @ StringNode (location: (10,2)-(10,7))
-        │   │   │   │   ├── flags: ∅
+        │   │   │   │   ├── flags: frozen
         │   │   │   │   ├── opening_loc: (10,2)-(10,3) = "\""
         │   │   │   │   ├── content_loc: (10,3)-(10,6) = "foo"
         │   │   │   │   ├── closing_loc: (10,6)-(10,7) = "\""
@@ -231,7 +231,7 @@
         │   │   ├── @ AssocNode (location: (13,2)-(13,14))
         │   │   │   ├── key:
         │   │   │   │   @ StringNode (location: (13,2)-(13,7))
-        │   │   │   │   ├── flags: ∅
+        │   │   │   │   ├── flags: frozen
         │   │   │   │   ├── opening_loc: (13,2)-(13,3) = "\""
         │   │   │   │   ├── content_loc: (13,3)-(13,6) = "foo"
         │   │   │   │   ├── closing_loc: (13,6)-(13,7) = "\""
diff --git a/test/prism/snapshots/unparser/corpus/literal/send.txt b/test/prism/snapshots/unparser/corpus/literal/send.txt
index 673787f1f1332f..edfd0cc6ae60aa 100644
--- a/test/prism/snapshots/unparser/corpus/literal/send.txt
+++ b/test/prism/snapshots/unparser/corpus/literal/send.txt
@@ -1310,7 +1310,7 @@
         │   │               └── @ AssocNode (location: (64,13)-(64,25))
         │   │                   ├── key:
         │   │                   │   @ StringNode (location: (64,13)-(64,18))
-        │   │                   │   ├── flags: ∅
+        │   │                   │   ├── flags: frozen
         │   │                   │   ├── opening_loc: (64,13)-(64,14) = "\""
         │   │                   │   ├── content_loc: (64,14)-(64,17) = "baz"
         │   │                   │   ├── closing_loc: (64,17)-(64,18) = "\""