diff --git a/include/prism/parser.h b/include/prism/parser.h
index b0ff2f38fcf..b35026e6a25 100644
--- a/include/prism/parser.h
+++ b/include/prism/parser.h
@@ -13,7 +13,6 @@
 #include "prism/util/pm_constant_pool.h"
 #include "prism/util/pm_list.h"
 #include "prism/util/pm_newline_list.h"
-#include "prism/util/pm_state_stack.h"
 #include "prism/util/pm_string.h"
 
 #include <stdbool.h>
@@ -612,6 +611,11 @@ static const uint8_t PM_SCOPE_PARAMETERS_FORWARDING_ALL = 0x40;
 static const int8_t PM_SCOPE_NUMBERED_PARAMETERS_DISALLOWED = -1;
 static const int8_t PM_SCOPE_NUMBERED_PARAMETERS_NONE = 0;
 
+/**
+ * A struct that represents a stack of boolean values.
+ */
+typedef uint32_t pm_state_stack_t;
+
 /**
  * This struct represents the overall parser. It contains a reference to the
  * source file, as well as pointers that indicate where in the source it's
diff --git a/include/prism/util/pm_state_stack.h b/include/prism/util/pm_state_stack.h
deleted file mode 100644
index 1ce57a2209f..00000000000
--- a/include/prism/util/pm_state_stack.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/**
- * @file pm_state_stack.h
- *
- * A stack of boolean values.
- */
-#ifndef PRISM_STATE_STACK_H
-#define PRISM_STATE_STACK_H
-
-#include "prism/defines.h"
-
-#include <stdbool.h>
-#include <stdint.h>
-
-/**
- * A struct that represents a stack of boolean values.
- */
-typedef uint32_t pm_state_stack_t;
-
-/**
- * Pushes a value onto the stack.
- *
- * @param stack The stack to push the value onto.
- * @param value The value to push onto the stack.
- */
-void pm_state_stack_push(pm_state_stack_t *stack, bool value);
-
-/**
- * Pops a value off the stack.
- *
- * @param stack The stack to pop the value off of.
- */
-void pm_state_stack_pop(pm_state_stack_t *stack);
-
-/**
- * Returns the value at the top of the stack.
- *
- * @param stack The stack to get the value from.
- * @return The value at the top of the stack.
- */
-bool pm_state_stack_p(pm_state_stack_t *stack);
-
-#endif
diff --git a/prism.gemspec b/prism.gemspec
index 6cf28460c2d..f4be1b36bbf 100644
--- a/prism.gemspec
+++ b/prism.gemspec
@@ -63,7 +63,6 @@ Gem::Specification.new do |spec|
     "include/prism/util/pm_list.h",
     "include/prism/util/pm_memchr.h",
     "include/prism/util/pm_newline_list.h",
-    "include/prism/util/pm_state_stack.h",
     "include/prism/util/pm_strncasecmp.h",
     "include/prism/util/pm_string.h",
     "include/prism/util/pm_string_list.h",
@@ -117,7 +116,6 @@ Gem::Specification.new do |spec|
     "src/util/pm_list.c",
     "src/util/pm_memchr.c",
     "src/util/pm_newline_list.c",
-    "src/util/pm_state_stack.c",
     "src/util/pm_string.c",
     "src/util/pm_string_list.c",
     "src/util/pm_strncasecmp.c",
diff --git a/src/prism.c b/src/prism.c
index 9c489e47856..18675b994a9 100644
--- a/src/prism.c
+++ b/src/prism.c
@@ -7632,6 +7632,30 @@ pm_parser_scope_pop(pm_parser_t *parser) {
 /* Stack helpers                                                              */
 /******************************************************************************/
 
+/**
+ * Pushes a value onto the stack.
+ */
+static inline void
+pm_state_stack_push(pm_state_stack_t *stack, bool value) {
+    *stack = (*stack << 1) | (value & 1);
+}
+
+/**
+ * Pops a value off the stack.
+ */
+static inline void
+pm_state_stack_pop(pm_state_stack_t *stack) {
+    *stack >>= 1;
+}
+
+/**
+ * Returns the value at the top of the stack.
+ */
+static inline bool
+pm_state_stack_p(const pm_state_stack_t *stack) {
+    return *stack & 1;
+}
+
 static inline void
 pm_accepts_block_stack_push(pm_parser_t *parser, bool value) {
     // Use the negation of the value to prevent stack overflow.
diff --git a/src/util/pm_state_stack.c b/src/util/pm_state_stack.c
deleted file mode 100644
index 2a424b4c03c..00000000000
--- a/src/util/pm_state_stack.c
+++ /dev/null
@@ -1,25 +0,0 @@
-#include "prism/util/pm_state_stack.h"
-
-/**
- * Pushes a value onto the stack.
- */
-void
-pm_state_stack_push(pm_state_stack_t *stack, bool value) {
-    *stack = (*stack << 1) | (value & 1);
-}
-
-/**
- * Pops a value off the stack.
- */
-void
-pm_state_stack_pop(pm_state_stack_t *stack) {
-    *stack >>= 1;
-}
-
-/**
- * Returns the value at the top of the stack.
- */
-bool
-pm_state_stack_p(pm_state_stack_t *stack) {
-    return *stack & 1;
-}