diff --git a/lib/cmock_header_parser.rb b/lib/cmock_header_parser.rb
index 3aaf9a1..260b73c 100644
--- a/lib/cmock_header_parser.rb
+++ b/lib/cmock_header_parser.rb
@@ -160,7 +160,7 @@ class CMockHeaderParser
         first_open_bracket = inline_function_match.post_match.index("{")
         first_semicolon    = inline_function_match.post_match.index(";")
 
-        if first_semicolon < first_open_bracket
+        if first_open_bracket.nil? or first_semicolon < first_open_bracket
           puts "DECLARATION, IGNORE"
           source = inline_function_match.pre_match + inline_function_match.post_match
           next
diff --git a/test/unit/cmock_header_parser_test.rb b/test/unit/cmock_header_parser_test.rb
index 70142a5..de12202 100644
--- a/test/unit/cmock_header_parser_test.rb
+++ b/test/unit/cmock_header_parser_test.rb
@@ -2119,6 +2119,19 @@ describe CMockHeaderParser, "Verify CMockHeaderParser Module" do
     assert_equal(expected, @parser.transform_inline_functions(source))
   end
 
+  it "Transform inline functions can handle header with only inline function declarations" do
+    source =
+      "static inline int dummy_func_decl(int a, char b, float c);\n" +
+      "\n"
+
+    expected =
+      "int dummy_func_decl(int a, char b, float c);\n" +
+      "\n"
+
+    @parser.treat_inlines = :include
+    assert_equal(expected, @parser.transform_inline_functions(source))
+  end
+
   it "Transform inline functions takes user provided patterns into account" do
     source =
       "static __inline__ __attribute__ ((always_inline)) uint16_t _somefunc (uint32_t a)\n" +