diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc b/libstdc++-v3/src/c++17/floating_from_chars.cc
index 13de1e346abb2677d3c18c9502ef603898056e3c..e7f3a58cf18f574f4d4c40ecd6b322588b15202d 100644
--- a/libstdc++-v3/src/c++17/floating_from_chars.cc
+++ b/libstdc++-v3/src/c++17/floating_from_chars.cc
@@ -664,7 +664,7 @@ namespace
 
     // Parse the written exponent.
     int written_exponent = 0;
-    if (first != last && *first == 'p')
+    if (first != last && (*first == 'p' || *first == 'P'))
       {
 	// Tentatively consume the 'p' and try to parse a decimal number.
 	const char* const fallback_first = first;
diff --git a/libstdc++-v3/testsuite/20_util/from_chars/7.cc b/libstdc++-v3/testsuite/20_util/from_chars/7.cc
index 2a78c7441e233030f784d6a1df1b920b2f142bcc..1aa9b23053162fbf590153d6ebc7497469fb68f5 100644
--- a/libstdc++-v3/testsuite/20_util/from_chars/7.cc
+++ b/libstdc++-v3/testsuite/20_util/from_chars/7.cc
@@ -96,6 +96,7 @@ constexpr testcase testcases[] = {
   { "1p-1", 4, {}, 0x1p-1 },
   { "0", 1, {}, 0.0 },
   { "A", 1, {}, 0xA },
+  { "1.ABCDEFP+10", 12, {}, 0x1.ABCDEFP+10 },
   { "-1", 2, {}, -1.0 },
   { "-0", 2, {}, -0.0 },
   { "42", 2, {}, 0x42p0 },