diff --git a/shared-module/dotenv/__init__.c b/shared-module/dotenv/__init__.c
index c09e38370b..24587247f0 100644
--- a/shared-module/dotenv/__init__.c
+++ b/shared-module/dotenv/__init__.c
@@ -137,7 +137,7 @@ STATIC bool key_matches(file_arg *active_file, const char *key) {
     if (character == '=' || character == '\n' || character == '#' || character == 0) {
         // Rewind one so the value, if any, can be found.
         seek_minus_one(active_file);
-    } else {
+    } else if (!unichar_isspace(character)) {
         // We're followed by something else that is invalid syntax.
         matches = false;
     }
diff --git a/tests/circuitpython/dotenv_test.env b/tests/circuitpython/dotenv_test.env
index 5e4e4cb8f0..7119774fa1 100644
--- a/tests/circuitpython/dotenv_test.env
+++ b/tests/circuitpython/dotenv_test.env
@@ -1,32 +1,23 @@
-# No e0 value
+# Key "notpresent" is not present
    # comment preceded by spaces
-e1=e1value
-e2=e2value # value followed by a comment
-e3='e3value'
-e4='e4value' # quoted value followed by a comment
-# e5 should be None
-e5
-# e6 should be the empty string
-e6=
-# e7 should be '#' (bash-like syntax processing)
-e7=#
-# e8 should be the empty string
-e8=''
-# e9 should be the empty string
-e9= #
-e10=e10_first
-e10=e10_last
-e11='abc#def'
-# e12 should be 'abc#def'
-e12=abc#def
-e12='multi
+plain_value=value
+value_with_comment=value # value followed by a comment
+quoted_value='value'
+quoted_value_with_comment='value' # quoted value followed by a comment
+should_be_none
+should_be_empty_string=
+should_be_hash=#
+quoted_should_be_empty_string=''
+duplicate_key=wrong
+duplicate_key=right
+value_with_hash=value#value
+quoted_value_with_hash='value#value'
+multi_line_value='multi
 line'
-e13=e13value
-e14  #comment
-e15 = e15value
-# e16 should be '#'
-e16=# #
-# e17 should be 'def#hi'
-e17='def'#hi
-# e18 should be '#has a hash'
-e18=#has a hash
+ space_before_key=value
+space_before_value= value
+space_before_hash_value= #value
+space_after_key =value
+space_after_key_before_value = value
+quoted_then_comment='value'#comment
+hash_with_spaces=#value value
diff --git a/tests/circuitpython/dotenv_test.py b/tests/circuitpython/dotenv_test.py
index 84856747f4..8445b98030 100644
--- a/tests/circuitpython/dotenv_test.py
+++ b/tests/circuitpython/dotenv_test.py
@@ -2,22 +2,24 @@ import dotenv
 
 FILE = __file__.rsplit(".", 1)[0] + ".env"
 
-print("e0", dotenv.get_key(FILE, "e0"))
-print("e1", dotenv.get_key(FILE, "e1"))
-print("e2", dotenv.get_key(FILE, "e2"))
-print("e3", dotenv.get_key(FILE, "e3"))
-print("e4", dotenv.get_key(FILE, "e4"))
-print("e5", dotenv.get_key(FILE, "e5"))
-print("e6", dotenv.get_key(FILE, "e6"))
-print("e7", dotenv.get_key(FILE, "e7"))
-print("e8", dotenv.get_key(FILE, "e8"))
-print("e9", dotenv.get_key(FILE, "e9"))
-print("e10", dotenv.get_key(FILE, "e10"))
-print("e11", dotenv.get_key(FILE, "e11"))
-print("e12", dotenv.get_key(FILE, "e12"))
-print("e13", dotenv.get_key(FILE, "e13"))
-print("e14", dotenv.get_key(FILE, "e14"))
-# print("e15", dotenv.get_key(FILE, "e15"))
-print("e16", dotenv.get_key(FILE, "e16"))
-print("e17", dotenv.get_key(FILE, "e17"))
-print("e18", dotenv.get_key(FILE, "e18"))
+print(f"notpresent={dotenv.get_key(FILE, 'notpresent')}")
+print(f"plain_value={dotenv.get_key(FILE, 'plain_value')}")
+print(f"value_with_comment={dotenv.get_key(FILE, 'value_with_comment')}")
+print(f"quoted_value={dotenv.get_key(FILE, 'quoted_value')}")
+print(f"quoted_value_with_comment={dotenv.get_key(FILE, 'quoted_value_with_comment')}")
+print(f"should_be_none={dotenv.get_key(FILE, 'should_be_none')}")
+print(f"should_be_empty_string={dotenv.get_key(FILE, 'should_be_empty_string')}")
+print(f"should_be_hash={dotenv.get_key(FILE, 'should_be_hash')}")
+print(f"quoted_should_be_empty_string={dotenv.get_key(FILE, 'quoted_should_be_empty_string')}")
+print(f"duplicate_key={dotenv.get_key(FILE, 'duplicate_key')}")
+### This is the a difference from CPython dotenv. The trailing #value is taken as a comment.
+print(f"value_with_hash={dotenv.get_key(FILE, 'value_with_hash')}")
+print(f"quoted_value_with_hash={dotenv.get_key(FILE, 'quoted_value_with_hash')}")
+print(f"multi_line_value={dotenv.get_key(FILE, 'multi_line_value')}")
+print(f"space_before_key={dotenv.get_key(FILE, 'space_before_key')}")
+print(f"space_before_value={dotenv.get_key(FILE, 'space_before_value')}")
+print(f"space_before_hash_value={dotenv.get_key(FILE, 'space_before_hash_value')}")
+print(f"space_after_key={dotenv.get_key(FILE, 'space_after_key')}")
+print(f"space_after_key_before_value={dotenv.get_key(FILE, 'space_after_key_before_value')}")
+print(f"quoted_then_comment={dotenv.get_key(FILE, 'quoted_then_comment')}")
+print(f"hash_with_spaces={dotenv.get_key(FILE, 'hash_with_spaces')}")
diff --git a/tests/circuitpython/dotenv_test.py.exp b/tests/circuitpython/dotenv_test.py.exp
index b6de0db390..d1cde70182 100644
--- a/tests/circuitpython/dotenv_test.py.exp
+++ b/tests/circuitpython/dotenv_test.py.exp
@@ -1,19 +1,21 @@
-e0 None
-e1 e1value
-e2 e2value
-e3 e3value
-e4 e4value
-e5 None
-e6 
-e7 #
-e8 
-e9 #
-e10 e10_last
-e11 abc#def
-e12 multi
+notpresent=None
+plain_value=value
+value_with_comment=value
+quoted_value=value
+quoted_value_with_comment=value
+should_be_none=None
+should_be_empty_string=
+should_be_hash=#
+quoted_should_be_empty_string=
+duplicate_key=right
+value_with_hash=value
+quoted_value_with_hash=value#value
+multi_line_value=multi
 line
-e13 e13value
-e14 None
-e16 #
-e17 def
-e18 #has a hash
+space_before_key=value
+space_before_value=value
+space_before_hash_value=#value
+space_after_key=value
+space_after_key_before_value=value
+quoted_then_comment=value
+hash_with_spaces=#value value